Ban Chiang, Northeast Thailand, Volume 2B: Metals and Related Evidence from Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang 9781931707923

Table of contents :
Contents
List Of Figures
List Of Tables
Contributors
1. Introduction to the Analyses of Metals and Related Evidence from Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang
2. Methods for Analysis of the Metal Artifacts
3. Classification of Metal Artifacts
4. Technical Analyses of Metal Artifacts: Results
5. Metal Product Manufacturing Evidence: Crucibles, Molds, and Slag
6. Depositional Contexts of Metals and Related Production Artifacts
7. Life History Perspectives on Metals and Related Finds
Appendix A: Supplemental Data Tables
Appendix B: Distribution Plans for Ban Chiang Non-burial Metal and Metal-related Artifacts by Site, Level, Square, and Quadrant
Appendix C: Glossary
References
Index

Citation preview

BAN CHIANG, NORTHEAST THAILAND, VOLUME 2B: METALS AND RELATED EVIDENCE FROM BAN CHIANG, BAN TONG, BAN PHAK TOP, AND DON KLANG

The microstructure of a lower Early Period amorphous artifact from Ban Tong. The copper-base metal is alloyed with 9% antimony, 1.5% arsenic, and 6% lead, with only trace amounts of tin. This unusual composition may be a result of early experimentation with alloys.

thai archaeology monograph series Series editor, Joyce C. White

Pietrusewsky, Michael, and Michele Toomay Douglas Ban Chiang, A Prehistoric Village Site in Northeast Thailand I: The Human Skeletal Remains, 2002. White, Joyce C., and Elizabeth G. Hamilton, editors Ban Chiang, Northeast Thailand, 2A: Background to the Study of the Metal Remains, 2018. White, Joyce C., and Elizabeth G. Hamilton, editors Ban Chiang, Northeast Thailand, 2B: Metals and Related Evidence from Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang, 2018. White, Joyce C., and Elizabeth G. Hamilton, editors Ban Chiang, Northeast Thailand, 2C: The Metal Remains in Regional Context, forthcoming. White, Joyce C., and Elizabeth G. Hamilton, editors Ban Chiang, Northeast Thailand, 2D: Catalogs for Metals and Related Remains from Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang, forthcoming.

University Museum Monograph 150

BAN CHIANG, NORTHEAST THAILAND, VOLUME 2B: METALS AND RELATED EVIDENCE FROM BAN CHIANG, BAN TONG, BAN PHAK TOP, AND DON KLANG

Joyce C. White and Elizabeth G. Hamilton, editors

university of pennsylvania museum of archaeology and anthropology philadelphia

library of congress cataloging-in-publication data Names: White, Joyce C., 1952- editor. | Hamilton, Elizabeth G. (Elizabeth Garrett), editor. Title: Ban Chiang, northeast Thailand. Volume 2B, Metals and related evidence from Ban Chiang, Ban Tong, Ban Phak Top, and don klang / Joyce C. White and Elizabeth G. Hamilton, editors. Description: Philadelphia : University of Pennsylvania Museum of Archaeology and Anthropology, 2018. | Series: University museum monograph ; 150 | Series: Thai archaeology monography series | Includes bibliographical references and index. Identifiers: LCCN 2018047881| ISBN 9781931707787 (hardcover : alk. paper) | ISBN 1931707782 (hardcover : alk. paper) Subjects: LCSH: Prehistoric peoples--Thailand--Ban Chiang (Udon Thani) | Metal-work, Prehistoric--Thailand--Ban Chiang (Udon Thani) | Ban Chiang (Udon Thani, Thailand)--Antiquities. Classification: LCC a-th--- | DDC 959.3/021--dc23 LC record available at https://lccn.loc.gov/2018047881

© 2018 by the University of Pennsylvania Museum of Archaeology and Anthropology Philadelphia, PA All rights reserved. Published 2018 Distributed for the University of Pennsylvania Museum of Archaeology and Anthropology by the University of Pennsylvania Press. Printed in the United States of America on acid-free paper.

dedication This volume is dedicated to Criswell Gonzalez, whose belief in the Ban Chiang Project and Joyce White and whose tireless support through building bridges and creating networks, enabled this monograph to come to fruition. Thank you, Cris, for being Joyce’s first footer in Hanoi on Tet in 1994.

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Contents

list of figures list of tables contributors 1

x xv xxviii



introduction to the analyses of metals and related evidence from ban chiang, ban tong, ban phak top, and don klang

Joyce C. White

1

2

methods for analysis of the metal artifacts

3



3

Elizabeth G. Hamilton

The Collection 3 Conservation 4 Databases and Recording 4 Methods of Metallurgical Analysis 6 Optical Metallography 6 Compositional Analysis 7 Microhardness 11 Previous Analyses 11 The Present Analysis 13 Comparing PIXE and SEM Analyses 14 Microhardness 15 Summary 15

classification of metal artifacts

Elizabeth G. Hamilton

17

Metal Artifact Classes 19 Personal Ornaments 20 Implements 25 Other 25 Metal Artifacts Recovered 36 Bangles 36 Bells 47 Adze/axes 48 Blades 49

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4

5

CONTENTS

Points 50 Miscellaneous Metal Artifacts 52 Wire/Rods 53 Flat Metal Artifacts 55 Amorphous Metal Artifacts 56 Artifact Classes through Time 58 Summary 58

technical analyses of metal artifacts: results

Elizabeth G. Hamilton and Samuel K. Nash

Metallography: An Introduction The Microstructure of Copper Alloys The Microstructure of Iron Technical Analysis of the Metal Analyzed Metals by Class Analyzed Metals by Site Analyzed Metals by Period Laboratory Analysis Compositional Analysis Fabrication Evidence Hardness Testing Analysis of Iron Variability in Fabrication Ban Chiang: BC Locale Ban Chiang: BCES Locale Ban Phak Top Ban Tong Don Klang Summary of Site Evidence Summary of Temporal Changes Alloys through Time Treatment through Time Summary and Conclusions

metal product manufacturing evidence: crucibles, molds, and slag

William W. Vernon, Joyce C. White, and Elizabeth G. Hamilton Crucibles The Study Corpus Methods of Analysis Ban Chiang Crucibles Ban Phak Top, Ban Tong, and Don Klang Crucibles Molds and Possible Molds Stone Mold Fragments Ceramic Mold Fragments Slag Discussion

61

62 62 70 72 73 73 73 73 76 80 87 88 90 91 91 93 93 93 93 96 96 97 100

103 103 104 104 108 115 117 117 117 119 120

CONTENTS

6

7

ix

Heat Delivery 121 Segmented and Decentralized Production 122 Casting 122 Continuity 123 Iron 124 Final Comments 124

depositional contexts of metals and related production artifacts

Elizabeth G. Hamilton and Joyce C. White

A Life History Framework Archaeological Contexts of Metal and Related Production Artifacts Grave Good Metals Metal Grave Goods from Ban Chiang Metal Grave Goods from Don Klang Summary of Metal Grave Goods Non-grave Good Metals Burial-associated Metals Feature Metals General Soil Matrix Metals Overview

life history perspectives on metals and related finds

Joyce C. White and Elizabeth G. Hamilton

Earliest Metallurgical Evidence at the Study Sites Copper-base Evidence at Ban Chiang Iron Evidence at Ban Chiang Early Metals from Ban Tong, Ban Phak Top, and Don Klang Summary of Earliest Metal Evidence Non-burial Use and Manufacture of Metal Artifacts Evidence for Manufacturing Non-burial Metals through Time Stratigraphic Context Summary of Non-burial Evidence Chronological Variation in Bangles Functional and Temporal Variation in Bangle Use Bangle Subtypes through Time Summary Interpretive Implications Regional Implications

appendix a: supplemental data tables appendix b: distribution plans appendix c: glossary references index

125 125 126 128 128 149 151 152 153 158 164 168

173

174 174 179 180 181 182 182 183 183 195 196 197 198 199 200 201

203 219 231 243 255

Figures (color insert appears between pages 124 and 125)

2.1 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 3.22 3.23 3.24 3.25 3.26 3.27

Photomicrograph of a lower Early period copper-base amorphous artifact with 9% antimony from Ban Tong Frontispiece Numbers of metal artifacts in the total study collection by site 4 Bangle terminology used in text 19 Bangle types as defined in text based on cross sections of bangle shafts 20 Copper-base bangles from Ban Chiang, Type A subtypes 21 Copper-base bangles from Ban Chiang, Type A-0 22 Copper-base bangles from Ban Chiang, Types B, C, Da, Db, with subtypes 23 Copper-base bangles from Ban Chiang, Types E–N 24 Copper-base bangles from Ban Phak Top, Ban Tong, and Don Klang 25 Iron bangles from Ban Chiang and Ban Phak Top 26 Copper-base bells from Ban Chiang and Don Klang 27 Adze/axes from Ban Chiang and Don Klang, copper-base and iron 27 BC Burial 23 with socketed copper-base adze/axe 28 Copper-base and iron blades from Ban Chiang and Don Klang 29 Iron blades from Ban Chiang 30 DK Burial 5 with iron blades and iron ball 30 Small copper-base points from Ban Chiang and Ban Tong 31 Bronze and bimetallic spear points from Ban Chiang 31 Iron points from Ban Chiang and Ban Phak Top 32 Unclassified iron points from Ban Chiang 33 Miscellaneous copper-base and iron artifacts from Ban Chiang, Ban Tong, and Don Klang 33 Selected copper-base wires from Ban Chiang, Ban Tong, and Don Klang 34 Selected copper-base and iron rods from Ban Chiang and Ban Tong 34 Selected copper-base and iron flat artifacts from Ban Chiang, Ban Tong, and Don Klang 35 Selected copper-base amorphous artifacts from Ban Chiang, Ban Phak Top, and Ban Tong 36 Copper-base grave goods from BC Burial 23 Color insert Three copper-base bells from the Late or Middle-Late Period Color insert BCES 395B/1115, a Type A-2 bangle from BCES Burial 12 Color insert BC 708A–C/1594, a matched set of anklets from BC Burial 49 Color insert

FIGURES

3.28 3.29 3.30 3.31 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8a 4.8b 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 5.1 5.2 5.3

Two views of BCES 532A–C/1601, iron and copper-base bangles from BCES Burial 26 Color insert Two bimetallic spear points from BCES Burials 24 and 80 Color insert BCES 762/2834, a socketed bronze spear point from BCES Burial 76 Color insert BCES 591/1981, a Type E-1 bronze bangle from BCES Burial 40 Color insert Photomicrograph of typical as-cast dendritic microstructure, with some corrosion 63 Photomicrograph of large cored dendritic structure, bronze or copper amorphous Color insert Photomicrograph of homogeneous polyhedral grains, along with gas or shrinkage voids 63 Photomicrograph of recrystallized grains with strain lines, 10% tin bronze Color insert Photomicrograph of flattened dendrites, the result of heavy working 64 Photomicrograph of recrystallized equiaxed grains with annealing twins, copper-base metal Color insert Photomicrograph of a hook-shaped bronze wire with 7% tin 65 The left side of the equilibrium copper-tin phase diagram 65 The left side of the copper-tin phase diagram under more realistic casting conditions for preindustrial contexts 66 The complete iron-carbon phase diagram 66 Photomicrograph of cored dendrites with intergranular α+δ eutectoid 67 Photomicrograph of cored dendrites with intergranular α+δ eutectoid in bronze amorphous piece Color insert Photomicrograph of bronze amorphous piece with α+δ eutectoid and corrosion 67 Photomicrograph of copper with annealing twins, redeposited in voids left by corrosion, bronze amorphous piece 68 Photomicrograph of high-tin bronze bangle quenched between 700°C–750°C Color insert Photomicrograph of high-tin bronze bangle quenched between 520°C–568°C 69 Photomicrograph of high-tin bronze flat piece quenched between 560ºC and 586ºC 69 Photomicrograph showing a color etch view of the same artifact as in 4.16 Color insert Photomicrograph of ferrite and slag stringers in an iron adze/axe 70 Photomicrograph of a gradient of carbon content in an iron blade 71 Photomicrograph of darker patches of possible bainite in an iron adze/axe 71 Graph of variation in hardness of alloyed copper and carburized iron with treatment 81 Photomicrograph showing an unclear but largely α phase structure in a fine wire 84 Crucibles from Ban Chiang 105 Crucibles from Ban Chiang 106 Drawing showing the layers of lagging on BC 975/786 107

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FIGURES

5.4

Lagging layers and oxidized copper on interior of Early Period– Middle Period crucible Color insert 5.5 Close-up of layers of lagging from reuse Color insert 5.6 Cross-section view of Late Period crucible showing slag and dross Color insert 5.7 Close-up of crucible showing copper prills trapped in slag Color insert 5.8 Cross section through Middle Period crucible, with slag, prills, and dross Color insert 5.9 Molds from Ban Chiang, Ban Tong, and Don Klang 118 5.10 Two intact crucibles and one large crucible fragment, all Middle Period Color insert 6.1a Drawing of BC Burial 14, the grave of a subadult from Late Period Phase X, with grave goods 135 6.1b BC Burial 14 high-tin bronze wire necklace Color insert 6.1c BC Burial 14 anklets 135 6.2 BC Burial 55, Late Period Phase X burial with a copper-base Type C-2 bangle 135 6.3a BCES Burial 7, Late Period Phase X burial of a middle-aged man with iron artifacts 136 6.3b Blade lying under the body of BCES Burial 7 136 6.3c Curved iron blade BCES 2004/2669 with intact wooden haft under the body of BCES Burial 7 136 6.3d Close-up of haft of BCES 2004/2669 from BCES Burial 7 136 6.3e Iron socketed spike and spear point next to left leg of BCES Burial 7 137 6.3f Close-up of iron spear point next to left leg of BCES Burial 7 137 6.4a BCES Burial 13, Late Period Phase X burial of an infant, with one iron blade 137 6.4b BCES Burial 13 with most of the grave goods removed 137 6.4c Iron blade BCES 394/1021 inside pot next to left foot of BCES Burial 13 137 6.5a BCES Burial 12, Middle Period Phase VIII burial of an infant 138 6.5b Drawing of BCES Burial 12 after the overlying sherd scatter had been removed 138 6.5c BCES Burial 12 after the overlying sherd scatter had been removed 138 6.5d Copper-base anklets from BCES Burial 12 138 6.5e Straight iron blade under BCES Burial 12 138 6.6a Illustration of fragmentary BCES Burial 23 from Middle Period Phase VIIb 139 6.6b Arm bones and bracelets from BCES Burial 23 139 6.7a BCES Burial 24, Middle Period Phase VIIb middle-aged man with bimetallic spear point 139 6.7b Close-up of bimetallic spear point from BCES Burial 24 139 6.8a BCES Burial 26, Middle Period Phase VIIb burial of a child with metal grave goods interred into BCES Burial 22 140 6.8b Metal grave goods of BCES Burial 26 in situ 140 6.8c Close-up of copper-base cuff bangle with iron bangles from BCES Burial 26 140 6.9 BCES Burial 80 with part of a bimetallic spear point 141 6.10a BCES Burial 40, Middle Period Phase VIIa skeleton of a middle-aged man with bronze bangle 141

FIGURES

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6.10b BCES Burial 40 after overlying sherd sheet had been removed 141 6.10c Close-up of Type E-1 bronze bangle with BCES Burial 40 141 6.10d Left lower arm of BCES Burial 40 with bronze and calcite Type E-1 bangles 141 6.11a BCES Burial 16, Middle Period Phase VIIa burial of an infant with copper-base anklets 142 6.11b BCES Burial 16 after the sherd sheet had been removed 142 6.11c Close-up of the copper-base anklets of BCES Burial 16 142 6.11d Close-up of the copper-base bracelet of BCES Burial 16 142 6.12a BCES Burial 14, Middle Period ?female infant with pig mandible and copper-base bangle 143 6.12b BCES Burial 14, arrow points to bangle BCES 1239/1114 143 6.13a BC Burial 49, a fragmentary Early Period–Middle Period burial of a child with five copper-base anklets 143 6.13b BC Burial 49, with copper-base bangles 143 6.14a BC Burial 23, a middle-aged man with copper-base grave goods from upper Early Period Phase Va 144 6.14b BC Burial 23 showing bronze grave goods 144 6.15a BCES Burial 38, a lower Early Period Phase IVc burial of a child with five copper-base bangles 144 6.15b BCES Burial 38 showing anklets 145 6.15c Close-up of anklets of BCES Burial 38 145 6.16a BCES Burial 76, a lower Early Period IIIa flexed burial with a bronze bent-tip spear point 145 6.16b Bent-tip spear point in grave of BCES Burial 76 145 6.17 Occurrence of bangle types in grave good and non-burial contexts at Ban Chiang 146 6.18a DK Burial 5, a Late Period mixed child/adult burial, with two iron blades and an iron ball 150 6.18b DK Burial 5 overview, showing iron grave goods 150 6.18c DK Burial 5 close-up of iron ball by right foot 150 6.19a DK Burial 8, Late Period adult male buried with two iron winged adze/axes 150 6.19b Close-up of iron adze/axe DK 302/457 from DK Burial 8 150 6.20 Proportions of burial and non-burial goods from Ban Chiang, Ban Phak Top, Ban Tong, Don Klang,and Ban Non Wat 171 7.1 The baked clay dump from casting hearth in BCES Square D5 Color insert 7.2 Ban Chiang non-burial metal and metal-related artifact classes by period 193 7.3 Frequency of Type A bangles from grave good versus non-burial contexts by period at Ban Chiang 198 7.4 Variation in burial and non-burial bangle closures at Ban Chiang by period 200 Appendix B Figures: Distributions of non-burial metals and metal-related artifacts B.1 BC Level 4 B.2 BC Level 5 B.3 BC Level 6 B.4 BC Level 7

220 220 221 221

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FIGURES

B.5 B.6 B.7 B.8 B.9 B.10 B.11 B.12 B.13 B.14 B.15 B.16 B.17 B.18 B.19 B.20 B.21 B.22 B.23 B.24 B.25

BC Level 8 BC Level 9 BC Level 10 BC Level 11 BC Level 12 BCES Level 2A BCES Level 2B BCES Level 2C BCES Level 2F BCES Level 2G BCES Level 2H BCES Level 3A BCES Level 3B BCES Level 3C BCES Level 3D BCES Level 3DE BCES Level 3E BCES Level 3F BCES Level 3G BCES Level 3H BCES Level 3I

222 222 223 223 224 224 225 225 225 226 226 226 227 227 227 228 228 228 229 229 229

Tables

2.1 2.2 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Prehistoric/Protohistoric Metal Artifact Numbers by Site 5 Comparison of the PIXE and SEM/EDS Results from Artifacts from Ban Phak Top, Ban Tong, and Don Klang 15 Metal Artifacts from All Sites in the Study 36 Artifact Counts by Class and Metal by Site 37 Distribution of Metal Artifact Classes by Period, All Sites Combined 37 Metal Bangle Types Recovered, All Sites Combined 40 Metal Bangle Counts by Type and Subtype, All Sites Combined 43 Bangle Types by Site/Locale 47 Metal Blade Types by Site/Locale and Period 49 Distribution of Metal Points by Site/Locale and Period 52 Miscellaneous Metal Artifacts 53 Distribution of Metal Wire/Rods by Site/Locale 54 Metal Wire/Rod Types by Site/Locale 54 Distribution of Wire/Rod Types by Period, All Sites and Metals Combined 55 Distribution of Flat Metal Artifacts by Site/Locale 56 Chronological Distribution of Flat Metal Artifacts, All Sites Combined 56 Distribution of Amorphous Metal Artifacts by Site/Locale 57 Chronological Distribution of Amorphous Metal Artifacts, All Sites Combined 57 Percentages of Artifacts Subjected to Metallography by Class 74 Distribution of Artifacts Analyzed Metallographically by Site and Class 74 Distribution of Artifacts Analyzed Metallographically by Period, All Sites Combined 75 Distribution of Artifacts Analyzed Metallographically by Period and Class, All Sites Combined 75 Copper-base Alloys Present from Metallography and Compositional Analysis by Site 77 Alloys of the Copper-base Analyzed Samples by Artifact Class, All Sites Combined 78 Alloys in Analyzed Sample by Period, All Sites Combined 79 Metallurgical Structures of the Copper-base Samples by Artifact Class, All Sites Combined 80

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TABLES

4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15

Post-casting Treatments of Copper-base Artifacts, Implements vs. Ornaments 83 Structures of Analyzed Quenched High-tin Bronze Artifacts by Site 85 Quenched High-tin Bronzes Analyzed from Ban Chiang and Don Klang 85 Summary of Evidence of Manufacturing in Iron Samples from Ban Chiang and Don Klang 89 Temporal Variability in Alloying & Manufacturing Techniques: BC 91 Temporal Variability in Alloying & Manufacturing Techniques: BCES 92 Temporal Variability in Alloying & Manufacturing Techniques: BPT 93 Temporal Variability in Alloying & Manufacturing Techniques: BT 94 Temporal Variability in Alloying & Manufacturing Techniques: DK 94 Manufacturing Techniques of the Copper-base Samples by Period 98 Ban Chiang Crucible Corpus 109 Ban Chiang Crucibles by Rim Shape 110 Ban Chiang Crucibles by Period 111 Temper Inclusions in Ban Chiang Crucibles 112 Lagging on Ban Chiang Crucibles 113 Slag and/or Glass on Ban Chiang Crucibles 114 Dross on Ban Chiang Crucibles 114 Observed Prills from Ban Chiang Crucibles 115 Crucibles from Ban Phak Top, Ban Tong, and Don Klang 116 Mold Pieces from Ban Chiang, Ban Tong, and Don Klang 117 Distribution of Slag Finds by Site and Period 120 Number of Metal Artifacts by Context Type for Each Site/Locale 128 Number of Metal-related Production Artifacts by Context Type for Each Site/Locale 129 Completeness of Bangles and Tools among Archaeological Contexts, All Sites Combined 129 Quantities of Metal Grave Goods by Site/Locale 130 Metal Grave Goods by Material and Class from Ban Chiang and Don Klang 130 Ban Chiang Burials with Metal Grave Goods 132 Ban Chiang Burials with Metal Bangles 134 Age, Sex, Period, and Phase of Ban Chiang Burials with Metal Grave Goods 147 Skeletons from Ban Phak Top, Ban Tong, and Don Klang by Age and Sex 149 Ban Chiang Burial-associated Metal Artifact Classes by Period and Material 154 Comparison of Ban Chiang Metal Artifact Classes by Context 155 Don Klang Burial-associated versus General Soil Matrix Artifact Classes 157 Metal Artifacts among Feature Types at Ban Chiang, Ban Phak Top, and Don Klang 159 Metal Artifact Classes and Crucibles by Feature Type at Ban Chiang 160 Copper-base Artifacts by Classes and Feature Types at Ban Phak Top and Don Klang 164

TABLES

6.16 6.17 6.18 6.19 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14

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Metal Artifact Classes from Ban Chiang General Soil Matrix 165 Metal Bangle Types from Ban Chiang General Soil Matrix 165 Metal Artifact Classes in General Soil Matrix at Ban Phak Top, Ban Tong, and Don Klang 167 Metal Bangle Types from General Soil Matrix at Ban Phak Top, Ban Tong, and Don Klang 167 Copper-base Metal and Related Finds from Lower Early Period Levels at BC and BCES 175 Context for Metal and Metal-related Artifacts from the Lower Early Period at Ban Chiang 176 Earliest Iron Finds at BC and BCES 180 Ban Phak Top Metal Artifacts by Level and Artifact Class 181 Metal Artifacts by Period and Context for Each Site/Locale 184 BC Locale Non-burial Metal Artifacts by Level, Square, and Metal Type 186 BC Locale Non-burial Copper-base and Iron Artifacts by Level and Artifact Class 187 BCES Non-burial Copper-base and Iron Artifacts by Level and Square 189 BCES Non-burial Copper-base and Iron Artifacts and Crucibles by Level and Artifact Class 190 Ban Phak Top Metal Artifacts and Crucibles by Level and Artifact Class 193 Ban Tong Non-burial Metals and Crucibles by Level and Artifact Class 194 Don Klang Non-burial Metals, Crucibles, and Slag by Level and Artifact Class 195 Ban Chiang Bangle Types in Burial/Non-burial Contexts 197 Copper-base and Iron Bangle Types by Period for BC and BCES 199

Appendix A Tables A.1 Metal Blades from Ban Chiang, Ban Tong, and Don Klang A.2 Metal Points from Ban Chiang, Ban Phak Top, and Ban Tong A.3 Elemental Compositions of Selected Copper-base Artifacts—PIXE A.4 Elemental Compositions of Selected Copper-base Artifacts—SEM/EDS A.5 Vickers Hardness Determinations for Selected Artifacts from All Sites A.6 Bangle Types in Ban Chiang Graves by Burial Phase A.7 Metal Bangle Grave Goods in Ban Chiang Graves by Type, Material, Burial, and Period A.8 Metal Grave Goods in Ban Chiang Graves by Class, Material, Burial, and Period, Excluding Bangles A.9 Burial-associated Metal and Related Production Artifacts from Ban Chiang A.10 Burial-associated Metal and Related Production Artifacts from Ban Tong and Don Klang A.11 Distribution of Crucibles and Crucible Characteristics at Ban Chiang

204 205 206 208 209 211 212 213 214 216 217

Contributors

Joyce C. White received her Ph.D. in Anthropology in 1986 from the University of Pennsylvania, with a dissertation on the chronology of Ban Chiang. She has been Director of the Penn Museum’s Ban Chiang Project since 1982 as well as a Senior Research Scientist and Associate Curator for Asia at the Museum, before founding and becoming the Executive Director of the Institute for Southeast Asian Archaeology in 2013. She is also currently an Adjunct Professor in Penn’s Department of Anthropology and a Consulting Scholar at the Penn Museum, where she continues her lifelong passion to foster scholarship of the prehistory of Southeast Asia with special emphasis on Thailand and now Laos. Joyce C. White Executive Director Institute for Southeast Asian Archaeology 3260 South St. Philadelphia, PA 19104-6324 [email protected] Elizabeth G. Hamilton received her Ph.D. in Anthropology from the University of Pennsylvania in 1995, with a dissertation on the development of the copper-working industry in late Iron Age and Roman Period Gaul. She has been working on the analysis of Southeast Asian metals since 1999. She is currently a Research Associate at the Institute for Southeast Asian Archaeology and a Consulting Scholar at the Penn Museum. Elizabeth G. Hamilton ISEAA/Ban Chiang [email protected]

James D. Muhly studied Classics and Ancient History, receiving his B.A. from the University of Minnesota in 1958. He was awarded a Ph.D. from Yale University in Assyriology and Near Eastern Archaeology in 1969. He taught at the University of Minnesota from 1964 to 1967, moving to the University of Pennsylvania in 1967. He retired as Professor Emeritus from the University of Pennsylvania in 1997, serving as Director of the American School of Classical Studies at Athens from 1997 to 2002. James has taught and published widely on various aspects of the history and archaeology of the Aegean and Near East, with special emphasis on metallurgy. He is currently studying the metal objects of the Petras cemetery. His Foreword to the Ban Chiang metals study is found in TAM 2A. James D. Muhly Proteos 36 Palio Faliron, Athens 175 61, Greece Samuel K. Nash received his Sc.D. in Metallurgy from the Massachusetts Institute of Technology in 1951. After 26 years as a physical metallurgist attached to the US Army Frankford Arsenal, he retired as the Chief of the Metals Engineering Branch. From 1953–1995, he served as Adjunct Professor and then Lecturer in Materials Science at Drexel University. After his retirement, he volunteered as a metallurgist at MASCA, the Penn Museum’s former Museum Applied Science Center for Archaeology, and in 2009 became a Consulting Scholar at the Museum. He retired from the Museum in 2016. Samuel Nash co-authored with Elizabeth Hamilton

CONTRIBUTORS

the metallographic and elemental analyses presented in TAM 2B, chapter 4. Samuel K. Nash 1420 Locust St.--9A Philadelphia, PA 19102 William W. Vernon received his Ph.D. in Geology from Lehigh University in 1964 and an M.S. in Anthropology from the University of Pennsylvania in 1984. He specialized in the analysis of minerals, rocks, and ceramics using microscopic methods. He was co-director of Archaeological Excavations in NY State from 1972–1980 and Project Geologist for the study of an ancient copper mine at Phu Lon in northeast Thailand in 1985 and 1988. He was also a member of MASCA and provided geological analysis for the studies of crucibles at Ban Chiang and Phu Lon. He retired as Emeritus Professor of Geology and Anthropology from Dickinson College in 1996. William Vernon conducted the study of the Ban Chiang crucibles presented in TAM 2B, chapter 5. William Vernon [email protected] Vincent C. Pigott holds a Ph.D. in Anthropology (1981) from the University of Pennsylvania, and since 1984 has been the co-director of the Penn Museum’s Thailand Archaeometallurgy Project. He is currently a Consulting Scholar in the Museum’s

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Asian Section. Previously he served as the Museum’s Associate Director and as a Senior Research Scientist in MASCA. After MASCA, he spent a decade as a Visiting Professor at the Institute of Archaeology, University College London. He is focused on the prehistory and archaeometallurgy of mainland Southeast Asia and maintains a strong interest in the origins, transmission, and societal impact of metallurgy across Eurasia. Vincent Pigott’s summary of prehistoric copper production evidence in Thailand and Laos is found in TAM 2C, chapter 2. Vincent C. Pigott [email protected] T. O. Pryce trained in archaeology and archaeological sciences at University College London and Sheffield University, completing his Ph.D. in Southeast Asian archaeometallurgy in 2009. He completed a Leverhulme Trust Early Career Fellowship at the University of Oxford and a Senior Post-Doctoral Fellowship with the Institut de Recherche pour le Développement before being recruited by the Centre National de la Recherche Scientifique (C.N.R.S.) in 2013. Pryce is currently a Researcher at the C.N.R.S, UMR 7528 Prétech and UMR 3685 NIMBE. Oliver Pryce’s lead isotope analyses of the Ban Chiang copper-base assemblage are presented in TAM 2C, chapter 3. T. O. Pryce [email protected]

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1 Introduction to the Analyses of Metals and Related Evidence from Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang Joyce C. White

T

he study presented in TAM 2B lays out and synthesizes the evidence from metals and related remains from four sites in northern northeast Thailand: Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang. The village societies living at these locations were mostly consumers of metal products, although discussion in Chapter 5 demonstrates that many final copper-base products were probably cast in those villages. The study aims to illustrate the value of analyzing full assemblages of metallurgical remains from anthropology of technology perspectives (TAM 2A, chapter 4) in order to understand ancient metals in their social contexts. In the following chapters, systematic assessments are made of typological range, variation in metal composition and manufacturing techniques, evidence for on-site production activities, and contextual evidence for deposition of metal finds. A far richer understanding of ancient metals is possible with this kind of comprehensive analysis, in contrast to approaches that try to generalize about ancient metallurgy from tiny samples that are inevitably biased. Analyses of excavated metal assemblages from the perspective of the New Archaeometallurgy Paradigm described in TAM 2A, chapter 4 have yet to become routine. In addition, the analyses of the metals from Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang began in the 1970s, long before there were any discussions of new paradigms for archaeometallurgical study (e.g., Thornton 2009b). In many ways, it was a happy coincidence that the recording system at these four sites was thorough and detailed

enough, as described in TAM 2A, chapter 2, that recovery contexts could be quantitatively delineated for not only metal grave goods, but also metals from non-burial contexts. Such documentation facilitates gaining perspective on the full roles and discard locations for metals in these prehistoric societies. It was also a happy coincidence that all metal remains from these sites were available in Philadelphia for sampling during the course of several archaeometallurgical classes taught at the University of Pennsylvania. Unfortunately, more commonly, excavated collections are split up and only small, biased samples are available for technical analyses. This practice results in distorted assessments for understanding metals in past societies. When it came time to compile the detailed evidence from these four sites into this study (TAM 2A–D), archaeological theory was catching up with the value of these assemblages, so that now they can shed important light on metal technological systems in non-urban, middle-range societies (see TAM 2C, chapter 6). But to get to that point, the evidence needs to be laid out in detail. To acquire the detailed evidence of the chaînes opératoires (see TAM 2A, chapter 7) present in archaeological metals assemblages, the archaeometallurgist must choose among many options. Chapter 2 lays out the methods used in the archaeometallurgical study of the four sites in the study collection. The condition of the collection, the recording systems, and technical analyses have their own histories, as artifacts were selectively conserved, or stored in various

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2B: THE METALS AND RELATED EVIDENCE

ways, as equipment or specialists were available, and as different participants came and went over the years. This multi-faceted history in the end allows for the thorough picture presented here. The comprehensive classification program presented in Chapter 3 includes all metal objects, intact or fragmentary, even if a function could not be assigned to the artifact. This approach is foundational to implementing a life history methodology to the assemblage analysis in Chapter 7. Fragmentary metal objects add information on compositional range and post-manufacturing treatments, even in the absence of information on what the object was designed to do. The potential role of objects in daily life requires a systematic assessment of broken and fragmentary artifacts. Moreover, study of potential manufacturing byproducts is key to examining the economic evidence for production activities at a site. The technical analyses presented in Chapter 4 provide the evidence for the past technological systems and their changes over time. Variability in chaînes opératoires as revealed in the compositional and metallographic analyses demonstrates how ancient metalworkers chose alloys and treatments for different classes of artifacts and how those choices changed over time (or not). Regional variation in metalworker know-how and choices can reveal past networks of communities of metallurgical practice that could have important ramifications for economic and social networks of the time as well as how these changed. Many metal age sites in Thailand, including those in this study, are blessed with numerous crucibles and fragments thereof. The study of these, as well as of molds and a few pieces of slag, in Chapter 5 sheds important light not only on the technological knowledge, skills, and techniques of the ancient metalworkers, but also on the organization of the metal

economy, particularly with regard to manufacturing final products. This study and the regional evidence presented in TAM 2C, chapters 4 and 5, clarifies how highly localized product preferences could be satisfied with a decentralized production system. A comprehensive analysis of depositional contexts from which the full metal assemblages have been recovered is presented in Chapter 6. All grave good metal artifacts are discussed as well as their burial contexts. Although many previously published studies of metallurgical evidence at Thai sites have emphasized grave goods, which usually comprise 10% or less of complete metallurgical assemblages in this region (see Fig. 6.20), all contexts are evaluated here. The data support the interpretation that metal was used in daily life, not just for prestige, wealth, or highly symbolic roles. Chapter 7 synthesizes the evidence from the previous chapters to illustrate how such detailed assemblage assessment provides the evidence for a life history perspective on archaeometallurgical evidence from metal age sites in Thailand. The stratigraphic evidence for the first appearances of metals in the site sequences is detailed. The non-mortuary use and manufacturing evidence over space and time is discussed for each site. Evidence for the chronological variation in burial and non-burial use of metals is articulated. The detailed assessment of the Ban Chiang, Ban Tong, Ban Phak Top, and Don Klang metal evidence from this anthropology of technology point of view (TAM 2A, chapter 4) enables these assemblages to be placed in a regional socio-technical framework not possible with an approach that studies only a few artifacts from an assemblage. The value of such finegrained analyses is illustrated in TAM 2C, chapters 4, 5, and 6, when the evidence from the four study sites is integrated with the larger regional evidence from northeast and central Thailand.

2 Methods for Analysis of the Metal Artifacts Elizabeth G. Hamilton

I

t has long been recognized that to understand the technology of manufacture, as opposed to simple visual assessment of artifact shape and decoration, it is necessary to employ a suite of techniques from the material sciences. Archaeometallurgists use optical metallography to discern techniques of forming and heat treatment, compositional analysis to determine elemental content and the quantities of alloying elements added, if any, and microhardness testing to determine if techniques have been applied to alter the hardness of the material. All these techniques have been applied to the present collection. This chapter describes both how the metal artifacts (including metal debris) were analyzed and the history of previous analyses of the metallic material. How the ceramic crucibles were analyzed is left for Chapter 5. One major objective of this analysis has been to base conclusions on robust samples. Earlier published analyses of the Ban Chiang metal artifacts were performed on tiny and unbalanced sample selections. Studies based on small samples unfortunately are common in the archaeometallurgical literature. Time, money, and expertise in technical studies are limited, and many analytical techniques require that a small piece be removed from the artifact, which is often resisted by excavators and curators. Sample size may also be limited because many artifacts are corroded, with little or no sound metal remaining. Even given these constraints, it is unfortunate that many published archaeometallurgical analyses present conclusions about the metallurgical technology

of a site or culture based on what can seem like a small, random assemblage of artifact samples, without acknowledging the biases in their sampling. This study subjected over 170 artifacts to metallographic analysis and over 50 to elemental analysis, and the variations that have been discovered show the dangers of confining analysis to only a few artifacts or time periods. Every effort was made to select samples of sound metal from a full range of artifacts, strata, and sites, which provides confidence that as much as possible of the copper-base, and to a lesser extent, iron technology practiced at Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang has been sampled. The methodology avoided analyzing fully corroded materials, even though such corroded samples can sometimes show remnant metallographic structures. This study is very fortunate to have had the opportunity to examine such a complete, well-documented, and relatively uncorroded collection of the products of a prehistoric metalworking technological system.

The Collection The collection whose analysis is presented in this volume is composed of 639 well-provenienced prehistoric and protohistoric artifacts excavated in 1974–1975 by the Penn Museum and the Thai Fine Arts Department. The artifacts come from the sites of Ban Chiang (BC and BCES locales), Ban Phak Top (BPT), Ban Tong (BT), and Don Klang (DK)

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(see Fig. 2.1 and Table 2.1). The total number of individual pieces in the prehistoric and protohistoric collection is actually greater than 639, because excavators sometimes grouped items with more than one piece under the same artifact number, under the assumption that at one time all the pieces belonged to a single artifact. Over a hundred Historic period or Recent metal artifacts were excavated as well, but they have been excluded from this study. TAM 2A, figure 2.7 and TAM 2A, table 2.1 can be consulted to see which levels at the study sites have been designated Historic or Recent. The plans in Appendix B exclude Historic and Recent artifacts from Ban Chiang BC Levels 13, BCES Levels 4A–4D, Ban Phak Top Levels 11–12, Ban Tong Levels 8b–9, and Don Klang Levels 4b–5. (Catalog 21 in TAM 2D contains a brief description of some of these Historic/Recent artifacts.) In 1976, the entire collection of metal artifacts, along with tons of sherds, pots, small finds, and other artifacts was shipped for analysis to the Penn Museum in Philadelphia on loan from the government of Thailand. In 1981, 30 metal artifacts considered most worthy of museum exhibit were incorporated into the Smithsonian exhibition Ban Chiang: Discovery of a Lost Bronze Age, which in 1987 was sent to Thailand for the permanent exhibition at the Ban Chiang National Museum. However, a small sample for metallurgical and compositional analysis was taken from nine of the 30 metallic artifacts returned to Thailand. These nine are included in the analytical results presented in Chapter 4.

Conservation After arriving in Philadelphia in January 1976, 96 artifacts (68 copper-base, 25 iron, and 3 bimetallic) were assessed and conserved in 1978 by Tamsen Fuller. The artifacts were evaluated for the degree of iron oxidation and bronze corrosion, impressions in the corrosion left by organic materials such as rice husks or textiles, and the components of the corrosion layers. Copper-base artifacts were first mechanically cleaned by scalpel, glass bristle brush, and/or a Vibrotool with a grinding head. The artifacts were then soaked in benzotriazole (BTA) in a vacuum to inhibit the corrosion process, rinsed in acetone, and

Figure 2.1  Numbers of metal artifacts in the total study collection by site. Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975; BT = Ban Tong; BPT = Ban Phak Top; DK = Don Klang.

brushed with three layers of Incralac, a preservative lacquer. The last layer also contained a silica-matting agent to render the lacquer matte rather than shiny. Iron artifacts were cleaned either with a stream of air abrasive aluminum oxide powder or by brush and Igepal (a non-ionic detergent). They were then rinsed, soaked in acetone or other dewatering solution, and wrapped in a cotton bandage to hold the artifact together. The artifacts were immersed in molten microcrystalline wax to give them a preservative layer. Excess wax was melted off with a hot air gun while the cotton bandage was being removed. From the time of conservation until 1999, the artifacts that were not included in the Smithsonian exhibition remained largely untouched and exposed to the open air, except for the occasional removal of small fragments for mounting and metallographic analysis. Some artifacts, especially those made of iron, were in notably worse condition than they had been in 1978. In 1999 and 2000, all the metal artifacts were put into padded containers inside plastic boxes equipped with silica gel desiccant.

Databases and Recording The initial database construction took place in 1978–1979. At that point it was decided to divide the metals collection into three broad groups: identifiable artifacts, artifact fragments, and “detritus.”

METHODS FOR ANALYSIS OF THE METAL ARTIFACTS

Table 2.1  Prehistoric/Protohistoric Metal Artifact Numbers by Site

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(e.g., wire/rods and flats) from objects that showed no evidence of deliberate shaping % of the Total (amorphous) and were potential casting dripNumber of Number of pings. She reorganized and recoded the entire Site (Locale) Artifactsa Metal Artifacts collection of fragments and detritus, including assigning fragments to specific classes such Ban Chiang (BC) 185 28.9 as bangles where possible. Ban Chiang (BCES) 218 34.1 By 1999, it had become apparent that Ban Phak Top 18 2.8 the metals databases needed to be revised and upgraded again. Mistakes and omissions had Ban Tong 116 18.2 been made in the earlier entries, inconsistenDon Klang 102 16.0 cies became evident, and some artifacts were Total 639 100% missing. The stratigraphy had also been thoroughly reappraised in the intervening years, Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975. so many of the artifacts had new level and aDoes not include four crucible prills and one slag prill. context designations. (As a result, the context data in the discussion in this volume supersede previous publications discussing metal grave goods, such as TAM 1.) In addition to the new level and context information, every artifact still at The identifiable artifacts were further subdivided the Penn Museum was reexamined in 2000 and new into bangles and “other” artifacts (mostly implemeasurements taken and entered into the Access daments). For the original mainframe database, the tabases. identifiable artifacts were coded according to the arOver the previous 25 years, black-and-white tifact class, such as bangles, points, and adze/axes. photographs had been taken of all the 639 artifacts Provenience entries and some measurements such as with good prehistoric provenience, along with color weight would be the same for each class, but each slides of the more complete artifacts. Over the same class would require different measurements to record period, drawings were made of most of the pieces it adequately. For example, bangles would require an with identifiable function (i.e., bangles, blades, etc.). internal diameter field and a shaft thickness field, A significant fraction of the collection consists of points would require a blade length, and so on. At small amorphous lumps and featureless flat pieces, that time, only minimal coding was done for metal and these were drawn only if a metallographic samfragments and detritus. The data, along with attenple had been taken. These drawings are shown in dant comments, were first entered into a mainframe Chapter 3. computer using SELGEM (Self Generating Master) Because all the information was entered into the (Hastings 1982). In the early 1990s, these data were 1990s databases according to the five artifact classes migrated into an IBM-PC database program called named above (bangles, artifacts, flat, wire/rods, and Paradox and were later moved into Microsoft Access amorphous), for simplicity this classification system and Microsoft Excel. has for the most part been retained in the present In the 1990s, Alissa Hinckley joined the Ban study. The only change is that the catchall class of Chiang Project as an undergraduate work-study stu“artifacts” has been divided into separate databases dent. She reviewed the categorization of the full metaccording to the morphology of the specific artifact; als assemblage and observed that a much more finei.e., blades, bells, adze/axes, points, and miscellagrained subdivision of the unclassified portion (the neous. Because most of the artifacts are fragmentary, vast majority of the metal objects) could be underinclusion into one of the classes was based on broad taken to include the shape categories wire/rods, flat, morphological traits. The artifact classes are defined and amorphous. One purpose of this reclassification and discussed in Chapter 3. was to distinguish fragmentary metal objects that Only a few of the morphological traits measured likely originated from deliberately shaped products and recorded in the databases are used in the analysis

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presented in this volume. Many of the measurements taken in the original data entry were judged to be unnecessary for the goals of this study. Nonetheless, all the recorded data are included and defined in the database found online, in the hope that these data might be useful for other scholars.

Methods of Metallurgical Analysis The metallic material from these four sites has been analyzed, both in this study and in previous work, using a variety of methods. Before discussing the work done on these metal artifacts by earlier researchers, a general description of the various methods of analysis is presented. Several different types of metallurgical analyses can be performed on metal artifacts, but the two most common and informative kinds are compositional analysis, which reveals the elemental composition of the metal or alloy, and optical metallography, which is the microscopic examination of a polished and etched metal sample. This visual examination can reveal something of the alloy composition of the artifact, how quickly the metal cooled from the molten state, and the processes—e.g., casting, hammering, annealing, quenching—that formed it. An ancillary technique of analysis is microhardness testing, which can reveal details of alloying, work hardening, and the technical suitability of artifacts to their suggested functions. The laboratory analysis of the metals from the four sites included all three types of analysis. Though some information can be obtained from the metallographic examination of corroded artifacts, examining sound metal is far more productive, and compositional analyses of corroded metal have little value. Thus, one of the major constraints on the successful analysis of ancient metal is the condition of the artifacts. In addition, when faced with a large collection of metals, as with the material from these four sites discussed below, it is necessary to sample the collection, using the criteria of soundness of metal, artifact class, chronology, and other archaeological considerations such as stratigraphic position, recovery context, and evidence of good provenience. Every effort should be made to choose as representative a sample as possible. Usually metallography precedes elemental analysis and hardness

testing in part because initial metallography will determine how interesting the structure is and whether the metal is sufficiently uncorroded that an accurate elemental reading can be obtained. As a result, the sample undergoing elemental analysis and the sample subjected to hardness will often be a subset of the sample receiving metallographic analysis.

Optical Metallography Optical metallography is the study of ground, polished, and etched samples of metal using a reflected light microscope designed for microscopy of opaque substances (Scott 1991). Optical metallography is an essential tool for understanding ancient metal artifacts. Under the microscope, metal artifacts retain traces of everything that has been done to shape them, and these traces do not fade through time. Using optical metallography, one can, from the appearance of the grains (crystals) and the material in the intergranular boundaries, frequently glean details of the nature of the alloy, the manufacturing technique, and the thermal history, such as quenching, annealing, or tempering.

Preparation Methods Optical metallography requires a metallic sample that is flat and polished. The less corrosion present, the better the potential for interpretation is. Misinterpretation of the metallic structure can be caused by surface deformation, smeared material, material (often corroded) pulled out of the surface by the process of grinding or cutting, and scratches (Scott 1991:69). In most cases, a small sample is removed from the artifact, preferably from an uncorroded portion. Care must be taken to ensure that the process of removal does not itself distort the metal, because any pronounced post-manufacturing stress, whether from use or analysis, can produce changes in the grain structure that are visible under the microscope. For this reason, it is best to use a low-speed, fluid-cooled saw rather than a jeweler’s hacksaw or snapping off a piece by hand, to minimize the chances for the analyst introducing structural change through friction heat or impact stress. After polishing, the sample is etched with a chemical etchant. Etchants preferentially attack

METHODS FOR ANALYSIS OF THE METAL ARTIFACTS

grain boundaries and strain markings and reveal internal features within grains. Good etchants for copper-base metals include a mixture of hydrogen peroxide and ammonium hydroxide, alcoholic or aqueous ferric chloride, potassium dichromate, ferric nitrate, or a combination of these etchants to bring out additional details. For details of etchants, see Scott (1991) and Vander Voort (1984). The etched samples are then examined under a metallographic microscope, using both bright light and polarized light. Polarized light is useful for identifying the composition of inclusions; for example, inclusions that are blue-gray under ordinary microscope illumination (bright light), become ruby red (if copper oxide) or black (if copper sulfide) under polarized light. Photomicrographs can then be taken, using a camera mounted on the microscope.

Compositional Analysis The primary method of elemental analysis used in identifying the major and minor alloying elements in the collection under study was PIXE (proton-induced X-ray emission spectroscopy), using NIST (National Institute for Standards and Technology) and BNF (British Non-Ferrous Metals) standards. A smaller number of artifacts were analyzed elementally by SEM/EDS, and a few by optical emission spectroscopy and X-ray fluorescence spectrometry (XRF).

PIXE The samples were analyzed at the Bartol Research Institute at the University of Delaware by Stuart Fleming of MASCA (the Museum Applied Science Center for Archaeology) and Charles Swann of the Bartol Institute. (For details of the Bartol system, see Fleming and Swann [1985] and Swann and Fleming [1986, 1988].) PIXE was chosen for several reasons: it can detect within 25–800 parts per million most of the elements of interest in ancient metal objects, such as lead, tin, antimony, and manganese (Fleming and Swann 1985), and it requires a very small amount of metal to be removed from the artifact. It can be completely nondestructive if a patch of patina can be polished off the artifact (Swann et al. 1992). In addition, all but the lightest elements

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can be analyzed simultaneously. The replicability, while varying with the inhomogeneity of the sample, averages 5–10%, which means that an analysis can be repeated on the same sample with only minor differences in the results. The accuracy varies with the quantity of a particular element, but when there is a large amount of a particular element, such as copper or tin in a bronze, the accuracy is 99% or better in an uncorroded sample (Stuart Fleming, personal communication 2001). PIXE testing can be performed rapidly: it takes 3–15 minutes to gather a PIXE spectrum, though analysis of the output can take much longer (Dran et al. 2000).

how pixe spectroscopy works The PIXE technique involves directing a microbeam of energetic light particles, usually protons, at the surface of an artifact or sample. The particles knock out electrons from the two inner shells (K and L) of an atom (Malainey 2011:487). Electrons drop from an outer shell to fill the vacancies, releasing excess electron binding energy. This excess energy is released as X-ray photons in specific wavelengths unique to each element, which can be represented graphically as spectra. The quantity of each element in the composition can be calculated based on the intensity of wavelengths that characterize that element. PIXE spectroscopy analyzes only the surface of a sample, as the proton beams go no deeper than about 10–20 microns in a copper-base sample (Fleming and Swann 1985). Because of corrosion, the surface of an archaeological artifact is unlikely to be of the same composition as the original artifact. This problem is solved in two ways: either the surface patina and corrosion layer can be ground or polished off in one area to reveal what is hoped to be clean metal, or a small fragment can be cut off the artifact and mounted with an interior surface of the sample exposed. This procedure, though mildly destructive, allows access to more reliably sound interior metal and permits metallography to be performed as well. The PIXE technique is notable for the versatility of its proton beam. In microbeam mode, the beam can be narrowed so that it covers an area only 50 microns in diameter, a great advantage when dealing with tiny copper prills or islands of metal remaining in a corroded matrix, or when trying to determine

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the elemental content of a solder. The proton beam can also be widened and used to scan an area of half a centimeter or more. In the case of the specimens under study here, a beam covering 2–3 mm was most commonly used (Stuart Fleming, personal communication 2001). Ancient metals tend to be very inhomogeneous by modern standards, with strong dendritic coring, segregated phases, and non-metallic inclusions left over from imperfect smelting. Nonetheless, these inhomogeneities are seldom larger than about 5 microns, so that the scanning proton beam should automatically average out the elemental quantities. Lead is the only element whose segregation patterns would lead to difficulty in detection with the PIXE beam (Stuart Fleming, personal communication 2001). Each element varies in its detection limit, or the quantity below which the PIXE technique cannot detect its presence. Detection limits are determined by background radiation (Bremsstrahlung radiation), detector resolution (the ability to separate X-ray lines of very similar energy values), and detection artifacts resulting from the equipment. (For a more technical description of PIXE spectroscopy and spectra analysis, see Dran et al. [2000].) With the proper selective filters, detection limits attained by PIXE spectroscopy can be at least 5–10 times better than X-ray fluorescence, another common method of elemental analysis (Guerra 2000). The Bartol system’s filters, by largely suppressing the background signal of major elements such as copper, kept the detection limits down in the 10–100 ppm range (Swann and Fleming 1988). All the analytical results from the PIXE study were normalized to 100%. Oxygen and other non-metallic elements were not measured. It should be noted that PIXE spectroscopy reads only the atomic composition, not different compounds. For example, it will not differentiate ferrous oxide (FeO) from ferric oxide (Fe2O3). Nor will PIXE spectroscopy differentiate between isotopes of the same element.

sources of error Various methods of compositional analysis have different advantages and disadvantages, but a study (Northover and Rychner 1998) of the comparability of results obtained by different analytical methods concluded that PIXE spectroscopy gave results that

conformed closely to the analytical standards. Nonetheless, two factors must be considered that may affect the reliability of the specific weight percentages of alloying elements. Lead is an important element in ancient metallurgy because when added to molten bronze or copper it lowers the melting temperature, softens the metal, and improves its castability. This ability was discovered in most bronze-using areas after a few centuries of bronze working. In addition, lead is easy to smelt and, because it is a byproduct of silver production, in most places it would have been readily available. When added to bronze it stretches out supplies of hard-to-obtain metal, an asset to thrifty smiths. If archaeologists want to assess the working properties of the metal of an artifact, it is essential to know something of the lead content. But because lead cannot dissolve in copper, it tends to segregate into discrete globules, so that any method of compositional analysis that involves focusing on a relatively small area, as does PIXE spectroscopy, could well miss an area of lead or by chance land on an area where lead has segregated. Software and multiple analyses are used to correct for the expected inhomogeneity of the lead, but the reader should be aware that there is a built-in error in the exact lead weight percentages in the tables in this volume, or, indeed, in any elemental analytical program dealing with archaeological metals. To correct this problem, three or four PIXE scans are taken on any sample that is suspected of being high in lead. This contrasts with the single scan that is usually considered sufficient for most samples (Stuart Fleming, personal communication 2001). Another source of error lies in the effects of corrosion. PIXE is a surface method; that is, it reads only a few tens of microns deep. Bronze is considerably more resistant to corrosion than iron, but continued exposure to air and ground water will lead to localized corrosion. (See Organ [1963] and Swann et al. [1992] for a detailed description of the chemical reactions involved in bronze corrosion.) As the corrosion progresses, lead globules will dissolve preferentially, resulting in pitting and more surface exposure. Stress lines produced when an artifact has been worked will also corrode preferentially, allowing corrosion cracks to penetrate deep into the artifact. Tin becomes enriched in the corrosion layer (Tylecote 1985); thus, a reading taken in an area heavy with

METHODS FOR ANALYSIS OF THE METAL ARTIFACTS

corrosion product can register a higher level of tin than was present in the original bronze. Corrosion raises the analyzed percentage of many trace and alloying elements. Swann et al. (1992) took multiple PIXE readings from 26 Mesopotamian artifacts: the first after polishing to brightness, and then more readings after repolishing and removing up to a half millimeter of metal. They found that the chlorine level (chlorine being crucially involved in the corrosion chemistry) was a useful guide to the degree of corrosion, and the chlorine percentage decreased after each polishing. They discovered that if they could reduce the chlorine percentage to below 0.2%, then the problem of elemental loss was considerably reduced. Below this percentage, further repolishing would not change the results of PIXE analysis; variations in results would be due only to local variations in composition. Analyses showing chlorine percentages higher than 0.2% are less certain. In the table of compositional results (Appendix A, Table A.3), both the chlorine percentage and the degree of corrosion (assessed by eye) are noted. In the metals studied here, the tin-rich α+δ eutectoid phase, when present, was the first phase to be corroded. Corrosion proceeds along the boundaries of the grains (see Fig. 4.12). After the tin-rich eutectoid has corroded away, the tin-rich areas of the dendrites are the next to follow, leaving behind copper-rich dendritic arms. Often the copper that has corroded away is redeposited as lumps of pure copper inside voids (see Fig. 4.13). The reddish copper color in those cases contrasts strongly with the paler color of the bronze, thereby allowing the analyst another means of identifying the alloy. Corrosion proceeds until only islands of metal are left. Almost no sampled artifacts are without at least mild corrosion. (The β-martensite high-tin bronzes were the most resistant.) Though the analysts were careful to grind away as much corrosion as possible, the extent of the corrosion produced by burial in a tropical climate meant that sometimes artifacts with severe corrosion had to be examined and analyzed by PIXE. All samples, however, had at least some visible uncorroded metal. As mentioned above, the higher the corrosion level, the more the elemental quantities obtained by PIXE that appear “exact” should be regarded as only semi-quantitative; the chlorine percentage, as noted, will serve as a guide. If, for instance, an artifact has a tin reading of 17%

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and a relatively high corrosion level, then the reader should conclude that while the original metal did indeed have a good deal of tin, the amount was unlikely to have been as high as 17%. The same is true of lead, arsenic, and antimony. This potential discrepancy is not as misleading as it might sound: a 10% tin-bronze will never be read as an impure copper, nor will a leaded bronze appear to be lead-free. The only uncertainty would come when percentages of approximately 2% tin or lead are recorded. In this study, when a given alloying element is present in percentages 2% or higher, then that metal is defined as a deliberate alloy. Consequently, a low or high reading around this cut-off point could lead to an alloy with only 1.5% tin in the original composition being classified as a deliberate bronze when a reading unaffected by corrosion would have classified it as an impure copper. With alloying elements in larger percentages, there will be no false positives or negatives, but the exact quantities given for the corroded samples must be treated cautiously.

X-ray Fluorescence (XRF) X-ray fluorescence spectrometry analyzes a surface by directing a beam of X-rays at the sample to eject electrons from the inner shells. After striking the sample, the X-rays are either scattered or absorbed, generating secondary X-rays with energies characteristic of all the elements that have been struck. These secondary X-rays hit a detector, which turns the rays into electrical pulses. The intensity of the pulses varies with the amount of the X-rays of each element, so the analysis can be at least semi-quantitative. The primary X-ray beam penetrates about 30–50 microns, but the depth of penetration depends on the percentage of heavy elements such as lead in the object, the angle of the primary beam, and the energy of the primary beam. The surface being analyzed need not be flattened or polished deeply, but because XRF is primarily a surface technique, it must be recognized that results will be affected by surface corrosion. Care must be taken to ensure that the surface is as representative as possible of the whole (Henderson 2000:15–16). One of the great advantages of XRF is that some units are portable and can be easily transported to the field or lab. If necessary, readings can be taken from

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surfaces, if no polishing or alteration is permitted. A vacuum is required to detect elements with atomic numbers below 13 (below aluminum). Because each element in the sample will emit several secondary X-rays with different wavelengths, interpretation of the results requires extensive calibrations by the software (Malainey 2011:482–483). In addition, usually only elements specifically searched for are detected, limiting the possibility of finding unexpected alloying or trace elements. XRF has two principal types: energy-dispersive spectrometry (ED-XRF) and wavelength-dispersive spectrometry (WD-XRF). Energy-dispersive spectrometry is nondestructive, and the secondary X-rays are separated by their energy levels and displayed in spectra. All elements are detected at the same time. Wavelength-dispersive spectrometry uses crystals that cause secondary X-rays to be diffracted at a particular angle, the angle being characteristic of the element. This extra dispersion allows for greater separation of the X-ray peaks and, thus, greater sensitivity, but at the cost of loss of speed. Wavelength-dispersive spectrometry also requires the sample to be powdered (Henderson 2000:16). Energy-dispersive spectrometry is cheaper and faster than WD-XRF, but less sensitive. A usable spectrum can be produced in 100 seconds with ED-XRF (Pollard and Heron 1996:48).

Scanning Electron Microscopy The primary use of SEM in archaeometallurgical studies is to examine compositionally heterogeneous structures, such as leaded bronzes and bronzes with different phases. SEM works by shooting electrons at an angle to the surface of the sample. This beam of electrons, when swept back and forth, produces a shadowing effect that reveals variations in composition and texture. When the electron beam hits the surface of the sample, it knocks out several types of electrons from the surface. Two types of electrons used in archaeological analysis are secondary electrons and back-scattered electrons. Secondary electrons are very low energy electrons pushed out of the outer orbitals of atoms in the very top of the sample. These electrons are used to map topographical variations, because projecting portions of the sample release more electrons than depressed portions. A topographical map of the surface can be constructed

by measuring the intensity of secondary electrons. Backscattered electrons have higher energy than secondary electrons and are knocked out from deeper layers. The intensity of back-scattered electrons is related not to the topography of the surface, but to the atomic weight of the nucleus struck. The intensity variations can be used to construct a map of the changes in composition across a surface (Henderson 2000:17–19). Like XRF, scanning electron microscopes can be operated with either a wavelength-dispersive X-ray spectrometer (WDS) or an energy-dispersive spectrometer (EDS). The SEM detector is attached to an image screen, where the movement of the electron beam across the surface of the sample is clearly shown. While SEM/EDS can be and is used to measure the composition of larger areas (see Appendix A, Table A.4 for the results of SEM/EDS analysis of artifacts from Ban Phak Top, Ban Tong, and Don Klang), its great advantage lies in its ability to move to any point on the surface and analyze this pinpoint. This makes it easy to conduct compositional analyses on phases and inclusions (Henderson 2000:17–19).

Optical Emission Spectroscopy Soon after the excavation of the materials in 1974–1975, a few metal artifacts from Ban Chiang were examined using optical emission spectroscopy (OES). In OES, the sample to be analyzed is either liquefied or dissolved in a solution, then nebulized, or converted into an aerosol and sprayed into a flame, furnace, or other heat source. This both atomizes the sample (breaks it down into atoms and ions) and excites the atoms through collisions. This briefly raises the energy level of the electrons (lifts them to a higher shell). The electrons then fall back to a lower, normal energy level, which releases energy characteristic of each atomic element. This energy release can be detected in the form of spectra by photographic plates or by slits and photomultipliers (Malainey 2011:446–447). The technique is rapid and requires only a small sample, but precision is low. The elemental composition is estimated from the degree of darkness of the spectral lines, so the results are only semi-quantitative. The OES technique has largely been replaced by X-ray fluorescence and other

METHODS FOR ANALYSIS OF THE METAL ARTIFACTS

emission methods with higher sensitivities and precision (Malainey 2011:447).

Choice of Method The accuracy of results from any analytical method depends on the carefulness of the sample preparation, the provision of good comparative standards, and the quality of the software used to correct the raw data. Optical metallography should be done whenever possible before the compositional analysis to gauge the degree of inhomogeneity of the metal. If the material is dendritic or otherwise inhomogeneous, a method should be chosen that uses a broader beam to take in a wider portion of the sample. The choice of method will also depend on the size of the sample to be removed or if any sample can be removed at all. In the end, though, the choice of method will probably depend largely on the cost and availability of the equipment. Northover and Rychner (1998) have shown that, while some methods and laboratories have limitations, in the main, the major modern analytical methods are all capable of producing accurate results that can be reproduced and compared to results from other methods.

Microhardness Alloying a metal can have considerable effects on its hardness. Alloying copper with tin or arsenic, for example, will produce a material that is harder than either of its components alone. An equally common way to increase the hardness of a metal is by hammering, or work hardening. Metal has a crystalline structure; pressure will cause a certain degree of slippage of the atomic planes. Hammering causes dislocations in the atomic planes, which pile up at the grain (crystal) boundaries. Eventually, after continued working, the dislocations pile up enough that no further deformation is possible, and the metal will crack. Annealing, or heating the metal to the point where recrystallization and release of the slip planes can occur, is the only way to prevent this cracking. Annealing softens the metal again so that further hammering can take place (Scott 1991:1–2). The hardness of a metal can be measured by its resistance to deformation produced by indentation with a known load. A Vickers microhardness test

11

is performed by pressing a tiny four-sided pyramidal diamond point into a selected area under controlled pressure and time, removing the load, and then measuring, under 400x magnification, the size of the resulting depression. The larger the depression measured, the softer the metal is. Five depressions are usually done for each desired sample or region and the results expressed either as an average or as a range of values, as in Table 4.11, Table 4.12, and Appendix A, Table A.5. Note that the results are expressed in traditional Vickers numbers, not in metric units. The point of the test is that alloying and work treatment will alter the hardness of a metal, and relative hardness measures allow assessment of degrees of work hardening and alloying that may not be apparent under the microscope. Both hammering and alloying have a great effect on copper. For instance, a cast, unworked copper has a Vickers hardness number range of 40–50, but a work-hardened bronze alloyed with 12% tin can be as hard as 220 (Scott 1991:82). Microhardness testing contributes not only to knowledge of the manufacturing techniques, but also allows the functionality of the metal for certain purposes to be assessed. The Vickers test is only one of several microhardness tests; others include the Brinell test, the Knoop test, and the Rockwell test. The Vickers and Brinell tests are most suitable for archaeological materials (Scott 1991:77). Although the Vickers and the Brinell scales are roughly comparable, at least up to approximately Vickers 500, the numbers produced by the other tests bear no relation to the Vickers scale. When looking at results produced by microhardness testing in other studies, the method type must always be noted (Scott 1991:77). A table that enables a conversion between the various methods can be found in Scott (2010:36).

Previous Analyses Copper-base and iron artifacts from Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang were the subject of several programs of analysis at the University of Pennsylvania in the past, as well as one program conducted at the University of Bradford (United Kingdom). The following is a brief overview of this research by the various teams of analysts involved. It is presented in the order—earliest

12

2B: THE METALS AND RELATED EVIDENCE

to latest—in which each analysis was performed or published. At the request of Ban Chiang Project co-director Chester F. Gorman, the first metallurgical analyses of artifacts from Ban Chiang were performed by Tamara Stech Wheeler and Robert Maddin at the Laboratory for Research on the Structure of Matter (LRSM) at the University of Pennsylvania (Stech Wheeler and Maddin 1976). Using optical metallography, they examined ten artifacts—bangles, wires, and spearheads—from Ban Chiang and eight artifacts from the site of Non Nok Tha, also in northern northeast Thailand. Although Stech Wheeler and Maddin examined 18 artifacts, only seven were discussed in their 1976 paper. Because the paper was written at a time when it was thought that the earliest metal at Ban Chiang dated to 3600 B.C., the chronology given in the 1976 paper is now considered incorrect. Stech Wheeler and Maddin’s conclusion was that most of the artifacts were approximately 10% tin bronzes, a typical percentage thought to be common in much of the ancient world, as a 10% tin content is optimal for casting, melting, and work hardening. Further analytical work, primarily metallography, on copper-base artifacts at Penn was performed as a part of various student class projects and master’s theses (e.g., Abiera 1978–1979; Haryono 1981; Natapintu 1981, 1982). The research was conducted jointly at MASCA and LRSM as part of a course in archaeometallurgy taught by Robert Maddin of LRSM and Vincent Pigott in the Penn Museum. Christine Abiera found that 13 of the 15 artifacts she studied were cast with no post-casting work to follow; the remaining two were of cast and hotworked high-tin bronze. Timbul Haryono examined ten artifacts from the survey sites of Ban Phak Top, Ban Tong, and Don Klang and came to the same conclusion: most were left in the as-cast condition, with some β-martensitic high-tin bronze and one bar that had been cast, worked, annealed, and then worked again. Surapol Natapintu in his master’s thesis (1982) examined six artifacts from Ban Chiang, all uniformly dendritic, i.e., left in the as-cast condition. In addition, he synthesized all previous metallographic work on Ban Chiang and survey metals up through 1981 (Natapintu 1982). In 1986, Stech and Maddin published a major reworking of their 1976 Ban Chiang analyses. (Their better known and more accessible 1988 paper

in the second BUMA [The Beginning of the Use of Metals and Alloys] volume is essentially the same paper as the 1986 publication.) They conducted metallographic analyses on 22 copper-base artifacts and three iron artifacts from Ban Chiang and added 20 compositional analyses by PIXE. The PIXE analyses were performed by Stuart J. Fleming, who directed the MASCA PIXE spectroscopy program jointly with Charles P. Swann of the Bartol Research Center at the University of Delaware. By this time, the chronology for Ban Chiang had been revised by White (1982:20, 1986) to suggest that the earliest metal artifact, a copper-base spear point, dated not to 3600 B.C. but to ca. 1700 B.C. This spear point had been analyzed by optical emission spectroscopy at LRSM in 1975 (Stech Wheeler and Maddin 1976). The analysis indicated that the metal contained only 1.3% tin. Stech Wheeler and Maddin suggested at that time that this was an indication of a “Copper Age,” a period of use of unalloyed copper that preceded the more sophisticated production of the copper-tin alloy, bronze. Optical emission spectroscopy is only semi-quantitative and a subsequent PIXE analysis of this artifact indicated that the tin level was between 7–9% (Stech and Maddin 1988). (A PIXE reanalysis in 1991 increased this to 9–11%.) Thus, what little evidence there was for a “Copper Age” at Ban Chiang disappeared. Nonetheless, Stech Wheeler and Maddin’s general conclusions from the 1976 paper stood: almost all the copper-base artifacts were bronze, with tin contents varying from 5% to 24%, The iron was uncarburized or partially carburized, with no sign of deliberate carburization or quenching. In the bronze, the only change noticeable through time was the appearance of lead in a few artifacts in the Middle and Late Periods. The alloys were uniform enough to suggest that the metalworkers were competent and had been so from the beginning of the use of metals at Ban Chiang. The PIXE analyses used by Stech and Maddin (1988) were performed at a time when the PIXE apparatus was being recalibrated (Stuart Fleming, personal communication 2001), and the elemental compositions presented in their paper probably should not be relied upon to be exact. PIXE reanalyses were performed on the same artifacts in 1991 by Fleming and Swann and those results are preferred if available.

METHODS FOR ANALYSIS OF THE METAL ARTIFACTS

Analytical work on early Southeast Asian iron began rather later than on the copper-base metal. Vincent Pigott (MASCA) teamed up with metallurgist Arnold Marder from the Homer Research Labs at Bethlehem Steel in Bethlehem, Pennsylvania, and using metallography and elemental analysis, they analyzed four iron artifacts from Don Klang, along with four additional iron artifacts from the nearby sites of Ban I Loet, Non Khao Wong, and Ban Puan Phu (Pigott and Marder 1984). All these artifacts came from prehistoric contexts. The artifacts from Don Klang were an adze/axe (DK 302/457), an iron ball or bell (DK 256/400), and a composite tool made up of a curved tanged blade and a flat blade (DK 255A&B/400). Samples were taken of both parts of this composite tool. During this analysis, degree of carburization, fabrication methods, possible heat treatment, and trace elements were all assessed. All four artifacts from Don Klang showed some degree of carburization, though probably not always deliberate. The iron bell or ball and the composite tool showed evidence of having been very slowly cooled. Pigott and Marder judged the adze/ axe (DK 302/457), however, to be composed of deliberately carburized steel that had been subjected to a relatively rapid air-cooling or quenching in liquid. They concluded that this tool, if the carburization and quenching were deliberate, represented “a major step in the development of working of iron as steel” in prehistoric Southeast Asia (Pigott and Marder 1984:289). By the early 1990s, under Pigott’s direction at MASCA, all the sampled metal artifacts with sound metal remaining had been mounted, polished, etched, and photographed. These samples then were all given a preliminary metallographic assessment by the team of Pigott and Dr. Harry Rogers, metallurgist and volunteer at the Penn Museum. Undergraduate anthropology student Alissa Hinckley, who did the sample preparation, entered the metallographic descriptions into a database at MASCA. Some of the photomicrographs from this stage in the investigation were used during the current study. The penultimate analysis of copper-base metal from the Ban Chiang Project sites was conducted by Alissa Hinckley for her master’s thesis at the University of Bradford, UK (1994). She examined 50 artifacts from Ban Phak Top, Ban Tong, and Don Klang, using optical metallography. Of these 50, 20

13

were also examined under backscatter electron imaging using SEM/EDS. The backscatter detector on the University of Bradford SEM used in Hinckley’s study attempted to collect both compositional and topographic information, and this caused some difficulty in distinguishing fine lead globules from the effects produced by surface relief (Hinckley 1994). Her overall aim was to present data on the nature of the artifacts and their method of manufacture, and to examine intersite variability in metalworking and use. She concluded that there were indeed some variations among the three sites, and her detailed conclusions are incorporated in the discussion section of Chapter 4. Hinckley also presented an extended discussion of the difficulties in doing elemental analysis on corroded samples.

The Present Analysis As can be seen from the foregoing summary, the published metallographic work on material from the four sites, especially those from Ban Chiang itself, has been limited and sporadic. For this monograph series, a full publication of the metals and their analyses was necessary. Rather than pulling together a patchwork of previous analyses done by people of varying experience and with equipment of differing reliability, it was decided that, to provide consistency, a single team should reanalyze all the metallographic samples. This team would also conduct further analyses and synthesize all the relevant data into a form that would not only present what is known of the metals and metal use in the four sites, but also place the metals of these sites in their regional, chronological, and socio-technical contexts. In 1999, the present author agreed to take on this work, with the invaluable laboratory assistance at MASCA of Dr. Samuel Nash, retired metallurgist and Penn Museum volunteer. Essentially, the metallographic analysis proceeded without reference to the conclusions of previous studies. Samples from two new artifacts were cut and mounted, but for the rest of the corpus the previously mounted samples were used, because samples from almost all the artifacts with sound metal had already been cut and mounted by previous analysts. These existing samples seemed to cover the full range of artifact classes, periods, and sites.

14

2B: THE METALS AND RELATED EVIDENCE

These samples were polished and etched afresh and examined under the microscope. All the samples, both from previous studies and the new samples, were cut from their parent artifact using a Buehler Isomet low-speed oil-cooled saw with a circular diamond blade. Some small artifacts were not cut, but mounted whole. In the case of artifacts with apparent cutting edges (e.g., points and adze/axes), the analysts tried to cut samples from the edge of the blade to see if distortions and/ or strain markings indicated that working to shape or to harden had been done. (Frequently, however, the edges were corroded and only the center of the artifact contained sound metal.) One spear point (BCES 762/2834) had samples taken from both the blade and the socket to compare the treatments the metal had received in the two locations. Therefore, while the number of metallic artifacts sampled was 171, the actual number of samples was 172. The samples were embedded in mounts made of either phenolic thermosetting plastic or cold-setting resin. The top surface of the mounts was ground down on water-lubricated grinding papers of 240-, 320-, 400-, and 600-micron (micrometer) grit. The ground surfaces were then rough polished with 9-micron and 1-micron diamond pastes. Further polishing was done with 0.3-micron de-agglomerated alumina powder mixed with de-ionized water, and a final finish was supplied by a polish with 0.05-micron alumina or colloidal silica. All polishing was performed manually. The polished samples were examined under the microscope before etching to assess the degree of porosity and corrosion as well as the size, shape, and distribution of inclusions. In the metallographic work done prior to 2000, all the copper-base samples were etched with a mixture of hydrogen peroxide and ammonium hydroxide (AH-HP) only. In the reanalysis performed in 2000–2001, the copper-base samples were first etched with AH-HP, and then, to reveal more detail, most samples were etched again with one or more of three different etchants: alcoholic ferric chloride, FeCl3; potassium dichromate, K2Cr2O7; or ferric nitrate, Fe(NO3)3. Iron samples were etched with both nital (ethanol and 2% nitric acid) and Marshall’s reagent (see Appendix C: Glossary for formula). The combination of these two etchants is best at revealing grain boundaries in low-carbon iron and steel, and nital also works well at revealing

the details of tempered martensite (Vander Voort 1984). The etched samples were examined under a metallographic microscope, using both bright light and polarized light. One or more photomicrographs were taken under bright light with Polaroid 4 x 5 positive/negative black-and-white film. The microscope used in this study was a Nikon Optiphot, a metallographic microscope designed for photomicrography, with available magnifications of 100x, 200x, 400x, and 600x. Photomicrographs had been taken of almost all the artifacts in the course of the analyses conducted by Pigott, Rogers, and Hinckley. When these old photomicrographs showed the same structure as that revealed by the etchants used by Hamilton and Nash, no additional photograph was taken. Usually this was not the case, because often the use of a different etchant from one used in the past revealed new structures that needed recording, or it was decided that a photograph at a different magnification or of a different region was desirable. As a result, most of the photomicrographs in this volume and online were taken in 2000–2001. By 1991, 20 PIXE analyses of 19 Ban Chiang copper-base artifacts had been performed. Hinckley (1994) analyzed an additional 20 copper-base artifacts from Ban Phak Top, Ban Tong, and Don Klang in 1993 using SEM/EDS. In 2000–2001, 24 additional PIXE analyses of 23 copper-base artifacts from Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang were conducted. (See Chapter 4 for results.) Nine of these new PIXE analyses were performed on artifacts already analyzed by Hinckley with SEM/ EDS. One 1991 PIXE analysis was discarded, leaving 52 copper-based artifacts analyzed. In addition, four iron artifacts had been analyzed before 2000, for a total of 56 artifacts analyzed elementally by PIXE or SEM/EDS.

Comparing PIXE and SEM Analyses Of the 52 artifacts subjected to either PIXE or SEM/EDS (EDAX) (in Hinckley 1994), nine artifacts were analyzed by both methods, and this provided a way to check on the comparability of the two methods. The compositional percentages from the nine artifacts are presented in Table 2.2. In most of the artifacts, the two methods of elemental analysis

15

METHODS FOR ANALYSIS OF THE METAL ARTIFACTS

Table 2.2  Comparison of the PIXE and SEM/EDS Results from Nine Artifacts from Ban Phak Top, Ban Tong, and Don Klang

Artifact ID BPT 23/79

PIXE Tin

SEM/EDS Tin

PIXE Lead

SEM/EDS Lead

PIXE Iron

SEM/EDS Iron

13.3%a

16%

—

—

—

—

BT 508/1081

9.3%

13%

—

—

—

—

BT 541/1214

0.54%

0.6%

—

—

—

—

BT 555/1303

6.4%

7%

—

—

—

—

BT 853/1634

0.03%

0%

0.06%

1%

—

—

BT 889/1694

6.9%

7%

0.06%

0.6%

—

—

DK 113/306

20.1%

23%

—

—

—

—

DK 134/328

44%

22%

—

—

—

—

DK 155/331

21.3%

25%

—

—

0.95%

1%

Note: BPT = Ban Phak Top; BT = Ban Tong; DK = Don Klang. aBecause PIXE gave percentages to several decimal places and the SEM/EDS gave percentages that were usually rounded to the nearest whole number, the PIXE and SEM percentages given in this table do not go to the same decimal place.

produced approximately the same results and are comparable, at least above the trace element level. The only major discrepancy was with DK 134/328, where the PIXE results showed an extraordinarily high level of tin. A reanalysis performed with the SEM/EDS at Drexel University in 2002 confirmed the Bradford SEM/EDS figure. Given this substantial agreement between the results of the two methods, it seems reasonable to assume that the Bradford SEM/EDS figures, though less precise than the PIXE percentages, are reliable approximations of the actual percentages of the major alloying elements in the eleven artifacts analyzed only by this method.

Microhardness Vickers microhardness tests were done on 31 copper-base and six iron artifacts. One iron sample and one bronze artifact were tested in two separate areas, for a total of 39 area tests. The microhardness testing in this study was performed with a Buehler Micromet II Vickers hardness tester. All the samples subjected to hardness testing in this study had previously been mounted and examined

metallographically. Phases and other areas of interest in each sample were distinguished under the 100x lens of the hardness tester. Five tests were made in each region of interest, using, with one exception, a load of 200 g applied for 15 seconds. Procedures followed the standards established by the American Society for Testing and Materials (ASTM, now known as ASTM International) in their 1981 publication. The results may be seen in Appendix A, Table A.5. In most cases, hardness impressions were sought from each phase available in a sample, i.e., dendrites and α+δ eutectoid in a bronze, and ferrite and carburized areas in an iron sample. In some samples of spear blades and adze/axes, when a cross-section sample had been taken, the microhardness tests were done in a line from the interior to the artifact edge, to see if there had been any working or special effort made to harden the edge.

Summary A total of 639 prehistoric metallic artifacts, along with 110 metal artifacts from historic/recent contexts, were excavated from the sites of Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang. One

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2B: THE METALS AND RELATED EVIDENCE

hundred seventy-one prehistoric artifacts were chosen for optical metallurgical analysis. The choice of which materials were sampled was based primarily on which artifacts had sound, uncorroded metal, but also on the desire to include a broad range of artifact classes, sites, and time periods, because a technological system cannot be reconstructed, even tentatively, from limited and unrepresentative samples of materials. Fifty-six of these 171 metal artifacts had in the past or in the course of this analysis been subjected to compositional analysis either by PIXE spectroscopy or SEM/EDS. Using nine artifacts that had been analyzed by both methods, results from the two methods were determined to be largely comparable. Thirty-five of the 171 also were subjected to Vickers microhardness testing.

The next chapter (Chapter 3) includes the typological (morphological) analysis of the metal artifacts. In Chapter 4, the results of the technical analyses are presented and combined with the information from the typological analysis into an evaluation of what artifacts were being manufactured, what alloys were being used, and what techniques were used to form the artifacts. Chapter 5 discusses the methodology and results produced by the analysis of the crucibles used to melt and refine the metal and the molds used to cast the artifacts. The technical analyses of all these disparate aspects of artifact production are necessary to allow reconstruction of the metallurgical technological system used during the metal age by the metalworkers at Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang.

3 Classification of Metal Artifacts Elizabeth G. Hamilton

T

he members of all societies share many similar physical and social needs. Study of the kinds of objects that are made to satisfy societal needs, such as tools for subsistence, weapons for defense, and ornaments for personal decoration, can reveal much about any society. Other classes of objects may not be so universally used, but be specific to the society, or to societies of different kinds of complexity. For example, large elaborately decorated drums, such as those found in Dian contexts from southwest China, are highly specific to that culture. Each society can fashion different types of artifacts to meet their common needs, use those artifacts in different ways, and invest them with different meanings, even if function may be identical. Ground stone adzes and iron hoes will both turn over the earth, obsidian knives and bronze daggers will both cut flesh, shell beads and diamonds set in gold will both ornament a wrist. The presence of one or another of these artifacts, though—ground stone versus iron, obsidian versus bronze, shell versus diamond—implies not only very different technological behaviors, but also significant differences in trade and procurement patterns, the organization of labor and product distribution, and the societal meanings of artifacts. The choices a society makes about what artifacts to fashion and what materials to use reveal much about its way of life, organization, and values. Investigation of a prehistoric society’s choices of and uses for material resources begins with the classification of excavated artifacts. Classification of artifacts provides a window not only into what the

ancient society needed in their material culture and saw as appropriate purposes for a technology and material, but also if and how those purposes changed over time. Moreover, the materials from which artifacts are made influence the physical characteristics, including morphology of the products. In an assemblage of jewelry, bangles made of shell are likely to have a range of morphological variation different from those made of metal or stone. The manufacturing techniques used have further implications for the possible morphologies that can be produced. Carving a bangle from stone or shell produces different morphological variations than casting or forging bangles from bronze or iron. Although in this monograph metal and metalrelated artifacts are discussed in isolation from other components of material culture, it is important to remember that in the prehistoric period at Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang, metal objects would have been relatively uncommon compared to, for example ceramic objects, and would have been surrounded by a host of tools and items made of other materials. Much of the material culture would have been of organic materials (e.g., basketry, textiles) and hence lost to the archaeologist. These organic artifacts might have been of greater utilitarian or social importance than the metallic artifacts. In the long run, the material culture made from metal must be integrated with the material culture made from other media. The justification for studying metal artifacts in isolation from all the artifacts present at a site is that the very presence of

18

2B: THE METALS AND RELATED EVIDENCE

metal alloy artifacts at any prehistoric site, as well as the artifacts used in their manufacture, implies much about the technological knowledge and interand intra-site social cooperation. White (1982, 1988) has argued, based on an initial assessment of metal grave goods, that copper-base metal was primarily used for personal ornaments in the Ban Chiang cultural tradition. Copper-base tools, while present, were less common and copper-base weapons almost nonexistent. Iron was initially used for both jewelry and implements and later used primarily for implements. To evaluate these arguments systematically, this study inventories the full range of metal artifact types and their probable functions and provides a quantitative analysis of the prominence of different artifact types in the total metals collection, including metals found both within burials and outside of burials. To analyze and discuss only the metal artifacts found in burials gives an incomplete picture of the role of metal in any society; at Ban Chiang and the other three sites, most of the metal and metal-related finds are from feature or general soil matrix contexts. Only analysis of the entire excavated assemblages of finds allows the possibility of beginning to understand the role of metal in all aspects of life: economic, craft, mortuary, and daily existence. In this volume, an artifact is any object showing human workmanship or modification. Thus, the definition of artifact used here includes the byproducts of manufacturing, as well as the finished objects and fragments. Casting spills and other debris of manufacturing are included under the term “artifact.” This chapter treats only objects that are composed of metal; crucibles, molds, and slag are dealt with in Chapter 5. Many classification systems are possible for these metal artifacts. They can be classified by their shape or form, by their presumed function, by their stratigraphic or chronological position, by their elemental content or mode of manufacturing, or by how the makers themselves classified the work of their hands. The classification schema presented in this chapter is one based primarily on material (metal) and visual assessment of form, i.e., morphology, as this is the easiest way of subdividing a large and disparate body of artifacts from numerous archaeological contexts. In many but not all cases, artifact forms can have functional implications. (For instance, intact bangles are highly unlikely to

be piercing implements, but was a spear point for killing or display?) For several reasons, other primary classifications were avoided. Technological analysis is expensive and difficult to perform on all artifacts. In prehistoric contexts, emic approaches to classification have limited plausibility. Although archaeologists may hope that their various classification schemes actually have some correspondence to how the makers saw and used their artifacts (Dunnell 1986; Spaulding 1953; Taylor 1948:113–151), ethnographic research has shown the extraordinary difficulty of reaching “folk” classifications, or “emic” categories, from artifact analyses, especially in prehistoric cultures (Rice 1987:277–282). Although important information could be derived from a typology based on temporally defined assemblages—collections of artifacts and features “that approximate as closely as feasible a sample of the objects used by a community or other small social unit during an interval in which little sociocultural change occurred” (Cowgill 1990:67)— this kind of assemblage analysis requires a fineness of temporal distinction that is not available in the stratigraphy of these tropical sites. Morphology-focused classifications, in contrast, can be done on most or all artifacts by eye and is independent of chronological, cultural, or contextual association, though the types created will almost certainly have chronological or contextual meaning. Formal analysis is a heuristic device that helps the archaeologist begin to create useful generalizations. One problem in many archaeological publications is when the types are presented as discrete and essential groups without the reader being able to see the range of variation in each type (Cowgill 1990). In this monograph, the authors have presented the drawings of all the intact metal artifacts and many of the fragmentary ones (see figures in this chapter) so that readers can see the justification for the type creation and to allow the readers, if they wish, to construct their own typologies from the data in order to answer their own questions. The first step in developing a classification scheme for metal artifacts from the four sites under study was to define groups of artifacts that had a high degree of internal or within-group morphological similarity and a low degree of similarity to other groups, or external isolation (Cowgill 1990; Rice 1987:274). The definition of artifact classes is in many cases

19

CLASSIFICATION OF METAL ARTIFACTS

unambiguous, but in other cases somewhat arbitrary. Similarly-shaped objects can be measured and classified by the same metric and qualitative observations, even when comparable function is not clear, in order to make formal comparisons. In some cases, function is known, as when a bangle is found around the wrist bones of a skeleton. Building on this approach, all artifacts that resemble these bracelets in form are classified as bangles, including arc fragments. The size of the circlet is not a primary consideration. The same observations and measurements can be recorded for a bracelet or a torc as for a finger ring, and their manufacturing process was presumably very similar. Therefore, all rings are classified as bangles irrespective of size even though one might be a finger ring and another an anklet. Even when the potential mechanical function of an artifact is clear, as with an intact bracelet or unbroken spear point, its cultural function may not be. Although assignment of an artifact to a class tends to be accompanied by assumptions as to the functional use of the artifact, these assumptions may not be warranted and are here not intended. An adze may have no utilitarian function at all and could have been intended and used primarily for display, gift

inside surface shaft interior diameter

exchange, or other economic or social roles. In cases of fragmentary and often corroded artifacts, assignment to an artifact class is not always clear-cut and functional connotations are even cloudier. Therefore, several classes that reflect a similar morphology but without a clear or unifying function (such as manufactured final products) have been created, namely flat, wire/rod, and amorphous.

Metal Artifact Classes The classification system used here includes both intact artifacts and fragments. Although function is implied in some of the categories, morphology is the primary basis for the subdivisions. The metal artifacts excavated at Ban Chiang (BC and BCES), Ban Phak Top, Ban Tong, and Don Klang are divided into nine classes, all at the same hierarchical level (Adams 1988:43). Some of these major classes are further subdivided into types, and occasionally subtypes. The classes are, for discussion purposes, put into three general categories with implied general functions: personal ornaments, implements, and other.

shaft height flange shaft width

opening outside surface

top surface bottom surface

shaft closure

closed circle bangle

overlapping bangle

band bangle

disk bangle C-shaped bangle

spiral bangle

Figure 3.1  Bangle terminology used in text.

cuff bangle

20

2B: THE METALS AND RELATED EVIDENCE

H A

I B J

C K

Da L

Db

M

E N

F

G

Figure 3.2  Bangle types as defined in this text based on cross sections of bangle shafts.

Personal Ornaments Bangles: curved lengths of metal with variable cross sections. Intact examples comprise a closed ring or rings with other kinds of closure such as spirals (see Fig. 3.1 for bangle terminology). The curvature and scale are such that the object could have fit

around a human body part. Fragmentary examples are arcs of the original circles. This class includes bracelets, anklets, necklaces, and finger rings. The bangles are further classified based on cross section morphology (Fig. 3.2). Subclasses for intact and nearly intact bangles are based on shaft closure variation (see Fig. 3.1; Table 3.4). Subtype 1 is a closed

21

CLASSIFICATION OF METAL ARTIFACTS

Type A-1

c

b

a Type A-2

e

d Type A-3

f

g

h 0

i

2cm

Figure 3.3  Copper-base bangles from Ban Chiang: Type A-1 (a) BC 693A–D/1203A, BC Burial 23. (b) BCES 596A/1984, BCES Burial 38. (c) BCES 1239/1114, BCES Burial 14. Type A-2 (d) BCES 395B/1115, BCES Burial 12. (e) BCES 617/2097. Type A-3 (f ) BC 2155/702. (g) BCES 494A/1438, BCES Burial 23. (h) BCES 494C/1438, BCES Burial 23. (i) BCES 495A–C/1438, BCES Burial 23. These are three bangles found together, not a single spiral bangle. Bangle closure subtypes (-0, -1, -2, -3, -4) are defined in Table 3.4.

22

2B: THE METALS AND RELATED EVIDENCE

Type A-0

a c

b

i

k

j

e

d

m

l

o

n

p

r s

t

u v 0

w

h

g

f

x

q

y

2cm

Figure 3.4  Copper-base bangle fragments from Ban Chiang: Type A-0 (a) BC 604A/492. (b) BC 679A–B/1071. (c) BC 713/893A. (d) BC 2156/322. (e) BC 2158/584. (f ) BC 2162/520. (g) BC 2168/1115. (h) BCES 205/379. (i) BCES 219/439. (j) BCES 238/490. (k) BCES 252/620. (l) BCES 253/595A. (m) BCES 269/672. (n) BCES 272/715. (o) BCES 302/799. (p) BCES 305/806. (q) BCES 317/863. (r) BCES 359B/996. (s) BCES 488/1408. Shaft diameter was increased by corrosion. (t) BCES 494B/1438, BCES Burial 23. (u) BCES 526/1592, BCES Burial 38. (v) BCES 594/1984, BCES Burial 38. (w) BCES 595/1984, BCES Burial 38. (x) BCES 606/2043. (y) BCES 1229/1077. (See also drawing of Type A-0 bangle BC 680/1071 in TAM 2D, catalog 1.)

23

CLASSIFICATION OF METAL ARTIFACTS

Type C-2

Type B-2

d b

a

c

Type Db-0

Type Da-0

e

i

f h

g 0

2cm

Figure 3.5  Copper-base bangles from Ban Chiang: Type B-2 (a) BCES 395A/1115, BCES Burial 12. (b) BCES 490/1286, BCES Burial 16. (c) BCES 492/1286, BCES Burial 16. Type C-2 (d) BC 704/1557, BC Burial 55. Type Da-0 (e) BC 720A/918, BC Burial 14. (f ) BC 720B/918, BC Burial 14. (g) BC 720C/918, BC Burial 14. (h) BC 720D/918, BC Burial 14. Type Db-0 (i) BC 2211/918, BC Burial 14.

24

2B: THE METALS AND RELATED EVIDENCE

Type E-1

Type F-0

Type F-3

c

b

d

a e Type G-2

f

Type I-0

Type H-0

g

h

i

Type J-0

k

j

l

m Type L-0

Type K-1

p Type M-0

n q Type N-1 o

0

2cm

r Figure 3.6  Copper-base bangles from Ban Chiang: Type E-1 (a) BCES 591/1981, BCES Burial 40. Type F-3 (b) BCES 491/1286, BCES Burial 16. Type F-0 (c) BCES 609/2069. (d) BCES 616/2097. (e) BCES 799/2549. Type G-2 (f ) BCES 359A/996. (g) BCES 375/1049. Type H-0 (h) BCES 129/142. (i) BCES 332/899. (j) BCES 649/2173. Type I-0 (k) BC 2159/593. (l) BCES 288/775. Type J-0 (m) BCES 347/950. Type K-1 (n) BC 708A–C/1594, BC Burial 49. (o) BC 709A–B/1594, BC Burial 49. Type L-0 (p) BC 2161B/781, BC Burial 14. Cross section is hollow. Type M-0 (q) BC 2160/276. Type N-1 (r) BCES 532A/1601, BCES Burial 26. Bangles wrapped around copper-base cuff are iron.

25

CLASSIFICATION OF METAL ARTIFACTS

Type A-0

a

Type F-0

b

d c Type I-0

Type H-0

g e

Type L-0

h

f 0

2cm

Figure 3.7  Copper-base bangles from Ban Phak Top, Ban Tong, and Don Klang: Type A-0 (a) BPT 57/107. (b) BT 480/813. (c) DK 209B/381. (d) DK 214/388. Type F-0 (e) DK 236/394. Type H-0 (f ) Two views of BT 514/1108. Type I-0 (g) DK 219/388. Type L-0 (h) DK 209A/381. (See also drawings of Type A-0 bangles BT 572/1372, BT 613/1426, and DK 212A/380 in TAM 2D, catalog 1.)

circle; subtype 2 is C-shaped; subtype 3 has overlapping ends; subtype 4 is a spiral. Subtype 0 is a bangle too fragmentary to determine closure type. Bells: small, round, rattle-type bells (clapper is loose within a globe), often with a small loop for attachment and a slit in the body (see Fig. 3.9a–f and Color Fig. 3.25).

Implements Adze/axes: implements with cutting edges usually on a splayed flat head with the blade transverse to and in alignment with the axis of the hafting element; all excavated examples are socketed, with straight, winged, and symmetrically splayed blades (see Figs. 3.10a–e, 3.11, and Color Fig. 3.24). Blades: implements whose primary working areas are cutting edges along a longitudinal side parallel to the axis of the hafting element, if present. Cutting edges can be either straight or curved. Hafting

elements include tangs, but some blades lacking these elements may have been hafted to wood or bamboo along the longitudinal side opposite the working edge (see Figs. 3.12–3.14). Points: small points, spear points, and other small and long, straight points that have a tapered end coming to a point extending from and in alignment with the hafting element. The shape implies that they were used to pierce an object. The cross section of the point can be flattened or round. The hafting element on complete examples is either a socket or a tang (see Figs. 3.15–3.18 and Color Figs 3.29–30).

Other Miscellaneous: artifacts, some probably fragmentary, that were clearly deliberately shaped but that are unique in the corpus or whose function is not clear and whose morphology does not fit other classes. The miscellaneous class includes a bronze

26

2B: THE METALS AND RELATED EVIDENCE

Type A-3

Type A-1

b c

a Type A-0

d

e

g

f

Type G-4

Type I-0

j

Type O-2

k

h

i

0

2cm

Figure 3.8  Iron bangles from Ban Chiang and Ban Phak Top: Type A-1 (a) BCES 530A/1601, BCES Burial 26. Type A-3 (b) BCES 531/1601, BCES Burial 26. (c) BCES 533/1601, BCES Burial 26. This artifact number comprises an indeterminate number of bangles, most broken, so their subtype is overlapping (A-3) rather than spiral. Type A-0 (d) BC 1115B/1406. (e) BC 1118/820. (f ) BCES 322/869. (g) BCES 532B–C/1601, BCES Burial 26. Type G-4 (h) BCES 745/2669, BCES Burial 7. (i) BCES 2064/850. Type I-0 (j) BC 2087/158. Type O-2 (k) BCES 1199/799. Shaft diameters of all but (e) were increased by corrosion; all the other Type A iron bangles shown here were assigned to Type A by estimating the degree of corrosion damage.

a b Figure 3.9  Copper-base bells from Ban Chiang and Don Klang: (a) BC 608/535. (b) BCES 162/205. (c) BCES 254/604A. (d) BCES 725/2511. (e) DK 211/380. (f ) DK 341/285.

c

d

e f 0

2cm

b a

c

d 0

2cm

e

Figure 3.10  Adze/axes. Copper-base adze/axe from Ban Chiang: (a) BC 694/1203A, BC Burial 23. Iron adze/axes from Ban Chiang and Don Klang: (b) BC 1100/141. (c) BC 1101A/336. (d) DK 283/445, DK Burial 8. (e) DK 302/457, DK Burial 8.

28

2B: THE METALS AND RELATED EVIDENCE

clay pellets Cu-base adze/axe BC 694/1203A disturbance disturbance

Cu-base bangles BC 693A–D/1203A

Figure 3.11  BC Burial 23 with socketed adze/ axe BC 694/1203A, beyond his left shoulder. Note copper-base bangles on left wrist.

animal bone N

0

50cm

side wall

knob that may have been a bangle adorno (decorative addition), a copper-base hook that was probably for fishing, two artifacts that may have been sockets, and other items whose function could not be guessed at but which clearly once had been part of a shaped item (see Fig. 3.19). Wire/Rods: a length of metal, more or less straight or slightly curved, of consistent width or slightly tapered, commonly with either a round or a square cross section. Wires range from 1–4 mm in thickness; rods are thicker than 4 mm. This division was originally defined by Alissa Hinckley and has been continued in this analysis. Burial context shows that some of the wires were parts of jewelry, but the function of the other examples, both wires and rods, is unclear. It should be noted that wires can be prominent in other prehistoric assemblages in Southeast Asia, i.e., the “wire bundles” excavated in Myanmar (Dussubieux and Pryce 2016); much more remains

to be learned about uses for this artifact class in the region. Some rods may have been parts of tools, such as tangs (see Figs. 3.20 and 3.21 for a selection of illustrations of wires and rods). Flat pieces: metal that has been deliberately shaped and whose breadth and length are much greater than the objects’ height, but whose original function cannot be determined. Some of these may well be fragments of other objects, such as blades or points. There are no set criteria for the length/ breadth ratio to qualify as flat; hence the assignment was made subjectively. Most of the flat pieces are small—96 of the 114 flat pieces have a maximum dimension of less than 4 cm. A few others are up to 8.7 cm long, but these are iron pieces distorted by corrosion (see Fig. 3.22 for illustrations of a selection of flat artifacts; these flat pieces were selected for illustration because they were analyzed by metallography, and in some cases, PIXE or SEM/EDS).

29

CLASSIFICATION OF METAL ARTIFACTS

a

b h

c

d

f

e

0

2cm

g

Figure 3.12  Blades. Unclassified copper-base blades from Ban Chiang: (a) BC 661/962. (b) BC 700/1487. (c) BCES 480/1367. Curved iron blades from Ban Chiang and Don Klang: (d) BCES 245/543. (e) BCES 1170/679A. (f ) BCES 2004/2669, BCES Burial 7. (g) DK 255A/400, DK Burial 5. Unclassified iron blade from Don Klang: (h) DK 255B/400, DK Burial 5.

30

2B: THE METALS AND RELATED EVIDENCE

a

b

c

f d

g

e

h

i

k j 0

2cm

Figure 3.13  Blades. Lunate iron blades from Ban Chiang: (a) BC 1120/885, BC Burial 14. (b) BCES 195/328. (c) BCES 399B/1115, BCES Burial 12. Straight iron blades from Ban Chiang: (d) BCES 352/959. (e) BCES 399A/1115, BCES Burial 12. (f ) BCES 516/1533, BCES Burial 80. Unclassified iron blades from Ban Chiang: (g) BCES 381/1067. (h) BCES 700/2397. (i) BCES 1147/627. (j) BCES 2003/543. (k) BCES 2044/1403, BCES Burial 7.

2 iron blades DK 255A&B/400

N

crushed skull baked clay iron ball DK 256/400 0

50cm

Figure 3.14  DK Burial 5. Only the legs are in anatomical position. The crushed skull is resting near the knees. The enigmatic iron ball/bell (DK 256/400) is near the ankles, and the linked iron blades (DK 255A&B/400) lie near where the pelvis would have been.

a Figure 3.15  Points. Small copper-base points from Ban Chiang and Ban Tong: (a) BC 715/1491. (b) BCES 397/1125. (c) BCES 741/2625. (d) BT 799/1565.

b

d c

0

2cm

a

c b

0

2cm

Figure 3.16  Spear points. Socketed bronze spear point from Ban Chiang: (a) BCES 762/2834, BCES Burial 76. Bimetallic socketed spear points from Ban Chiang: (b) BCES 548/1582, BCES Burial 80. (c) BCES 573/1813, BCES Burial 24.

32

2B: THE METALS AND RELATED EVIDENCE

a

c

b

e d

0

2cm

f

Figure 3.17  Iron Points. Socketed iron spear points from Ban Chiang and Ban Phak Top: (a) BC 1109/614. (b) BCES 749/2669, BCES Burial 7. (c) BPT 363/47. Sockets of Figures 3.17a–b are completely closed by corrosion. Tanged iron spear point from Ban Chiang: (d) BCES 426B/1222, BCES Burial 7. Iron socketed spikes from Ban Chiang: (e) BCES 350/955. (f ) BCES 1205/850, BCES Burial 7.

33

CLASSIFICATION OF METAL ARTIFACTS

Figure 3.18 left  Unclassified iron points from Ban Chiang: (a) BCES 426A/1222, BCES Burial 7. These two pieces were probably part of one artifact. (b) BCES 772/2371.

a

b 0

2cm

Figure 3.19 right  Miscellaneous copper-base artifacts from Ban Chiang and Ban Tong: (a) BC 2207/355. Possible bangle adorno. (b) BT 890/1696. Fish hook. Miscellaneous iron artifacts from Ban Chiang and Don Klang: (c) BC 1101B/336. Socket. (d) BCES 1109/251. Socket. (e) DK 256/400, DK Burial 5. Large bell or cleft ball.

a b

d

c

e 0

2cm

34

2B: THE METALS AND RELATED EVIDENCE

e

g

f

d

j

Figure 3.20 left  Wires. Selected copper-base wires from Ban Chiang, Ban Tong, and Don Klang: (a) BC 633/770, BC Burial 14. (b) BC 2161A/781, BC Burial 14. (c) BC 2208/918, BC Burial 14. Five of more than 50 fragments. (d) BT 508/1081. (e) BT 853/1634. (f ) BT 889/1694. (g) DK 134/328. (h) DK 149/329. (i) DK 153/332. (j) DK 176A–B/362. DK 176A is one longer piece; DK 176B is three smaller pieces. (k) DK 261A/405. 13 of 15 pieces. Selected iron wires from Ban Chiang: (l) BC 1108/593. At least two pieces and several lumps of corrosion. Drawings without cross sections were made from the mounted artifact.

c

b

a

h

i

k 0

a

l

2cm

b

d

c

e

f g

j

i

h

k

l m

o

p

r

q 0

n

2cm

s

t

Figure 3.21 above  Rods. Selected copper-base rods from Ban Chiang and Ban Tong: (a) BC 645C/870. (b) BC 685/1089. (c) BC 698B/1426. (d) BC 2188/530. (e) BCES 312/854. (f ) BCES 458/1309. (g) BCES 486/1395. (h) BCES 502/1460. (i) BCES 528/1595. (j) BCES 621/2031. (k) BCES 696/2388. (l) BT 506/982. (m) BT 541/1214. (n) BT 555/1303. Selected iron rods from Ban Chiang: (o) BC 2218/495. (p) BCES 435/1233. (q) BCES 452/1273. (r) BCES 472/1335. (s) BCES 748/2669, BCES Burial 7. (t) BCES 761/2826.

35

CLASSIFICATION OF METAL ARTIFACTS

a

f

c

b

g

e

d

j

i

h 0

k

m l

2cm

Figure 3.22  Selected copper-base flat artifacts from Ban Chiang, Ban Tong, and Don Klang: (a) BC 601/277. (b) BC 602/284. (c) BC 656B/928. (d) BCES 237/516. (e) BCES 546/1662. (f ) BCES 742/2635. (g) BCES 1230/1118. (h) BCES 2009/391. (i) BT 532/1173. (j) BT 534/1176. (k) DK 109/287. (See also drawing of BT 726/1507 in TAM 2D, catalog 15.) Selected iron flat artifacts from Ban Chiang: (l) BC 712/887. (m) BCES 179/271. These flat pieces were selected for illustration because they were analyzed by metallography and, in some cases, PIXE or SEM/EDS.

Amorphous artifacts: irregular lumps of metal. Some may once have been part of an object, but most were probably casting splashes or other byproducts resulting from metal smelting or melting; i.e., most amorphous items were not deliberately shaped. The amorphous class does not include slag. Slag is discussed in Chapter 5 along with the other metal-related artifacts and byproducts (see Fig. 3.23, which illustrates a few of the amorphous pieces; these pieces were selected for illustration because they were analyzed by metallography, and in some cases, PIXE or SEM/EDS). As the fragmentary metal objects were assigned to classes, it became clear that the boundaries between amorphous, flat, wire/rod, and bangle were not firm. A number of objects could easily have been put in more than one category and choice of category in those cases is somewhat arbitrary. The 639 metal artifacts excavated from both prehistoric and protohistoric mortuary and occupation contexts at Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang include a wide variety of artifact types of both copper-base and iron. Five hundred fourteen artifacts (80.4%) are of copper-base metal, 123 of iron (19.2%), and two are bimetallic spear points whose hilt is of copper-base and blade is of iron. The numbers of copper-base and iron artifacts by site can be seen in Table 3.1. As the table shows, the Ban Chiang site contained almost all the iron artifacts and both bimetallic

artifacts. This is true not only of absolute numbers of artifacts but also the proportions; 26.4% of all the metal artifacts recovered from the two Ban Chiang locales are iron or bimetallic, but only 7.6% of the artifacts from Ban Phak Top, Ban Tong, and Don Klang are iron. In view of the very small quantity of slag found at Ban Chiang, it is likely that iron smelting or working was not customarily carried out at Ban Chiang, at least near the excavated areas, but the disproportion in the percentage of iron does suggest that the people of Ban Chiang had greater access to iron than the inhabitants of the other sites. The distribution among classes for the metals recovered from the four sites is presented in Table 3.2. Artifacts that appear to be byproducts of on-site metal product manufacturing activities, namely amorphous pieces, are the most common metal artifacts found. Among finished products intact enough to assign a possible function, personal ornaments, particularly bangles, are more common than tools such as adze/ axes, points, and blades. At least 100 metal artifacts, representing a wide range of artifact classes, were excavated from each site except Ban Phak Top. Table 3.3 shows the distribution of the metal artifact classes through time, all sites combined. The largest class in every period except for the Late Period–Protohistoric is amorphous. Flats and wire/ rods are also important in every period, followed by bangles. The numbers of identifiable ornaments (116 bangles and bells) is considerably larger than the

36

2B: THE METALS AND RELATED EVIDENCE

c

b

a

i

d

k

j

q

f

e

g

m

l

0

o

n

s

r

h p

u

t

v

2cm

Figure 3.23  Selected copper-base amorphous artifacts from Ban Chiang, Ban Phak Top, and Ban Tong: (a) BC 603/471. (b) BC 613/582. (c) BC 621/676. (d) BC 647A/890. (e) BC 647B/890. (f ) BC 652/912. (g) BC 678A/1063. (h) BC 703/1545. (i) BC 719/1589. (j) BC 2123/811. (k) BCES 278/729. (l) BCES 299A/791. (m) BCES 364/1010. (n) BCES 601/2021. (o) BCES 708/2436. (p) BCES 729/2548. (q) BCES 807/2576. (r) BCES 820/2743. (s) BCES 1402/1320. (t) BPT 14A/67. (u) BPT 27/85. (v) BT 812/1581. These particular amorphous pieces were selected for illustration because they were analyzed by metallography, and in some cases, PIXE or SEM/EDS.

Table 3.1  Metal Artifacts from All Sites in the Study

Ban Chiang (BC and BCES locales)

Ban Phak Top

Ban Tong

Don Klang

Copper-base

296

15

114

89

Iron

105

3

2

13

2

—

—

—

403

18

116

102

Bimetallic Total

Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975.

number of identifiable tools (49), though the proportion of identifiable tools (adze/axes, blades, points, and miscellaneous) to the total number of metal finds rises through time, from 3.5% in the Early Period to 10.9% in the Late Period and 15.4% in the Late Period–Protohistoric. A few tools are of copper-base in the earlier levels, but not until the Middle and Late Periods, with the introduction of iron, are a substantial number of intact metal tools recovered. Despite this, it is likely that even in the iron-using period most tools used in daily life were of wood and bamboo. Below, each class is discussed in more detail with regard to typological variation, size range, and other

characteristics, as well as presence at the five excavation locales.

Metal Artifacts Recovered Bangles Metal circlets and fragments of circlets are grouped together under the class of bangle. These artifacts are among the most common finished metal artifacts in

37

CLASSIFICATION OF METAL ARTIFACTS

Table 3.2  Artifact Counts by Class and Metal, by Site

BC & BCES Cu

Fe

Bi

79

13

Bell

4

Adze/axe

1

Blade

BPT

BT

DK

Total

%

Total

Cu

Fe

Total

Cu

Fe

Total

Cu

Fe

Total

—

92

4

—

4

4

—

4

10

—

10

110

17.2

—

—

4

—

—

0

—

—

0

2

—

2

6

0.9

2

—

3

—

—

0

—

—

0

—

2

2

5

0.8

3

16

—

19

—

—

0

—

1

1

—

2

2

22

3.4

Point

4

7

2

13

—

1

1

1

—

1

—

—

0

15

2.3

Misc.

1

4

—

5

—

—

0

1

—

1

—

1

1

7

1.1

Wire/Rod

26

10

—

36

1

1

2

31

—

31

46

2

48

117

18.3

Flat

45

38

—

83

2

—

2

21

1

22

5

2

7

114

17.8

Amorphous

133

15

—

148

8

1

9

56

—

56

26

4

30

243

38.0

Total

296 105

2

403

15

3

18 114

2

116

89

13

102

639

Bangle

Note: BC & BCES = Ban Chiang, BC (Ban Chiang 1974) and BCES (Ban Chiang Eastern Soi 1975) locales combined; BPT = Ban Phak Top; BT = Ban Tong; DK = Don Klang; Cu = copper-base; Fe = iron; Bi = bimetallic; Misc. = miscellaneous.

Table 3.3  Distribution of Metal Artifact Classes by Period, All Sites Combined

Class

EP

EP–MP

MP

MP–LP

LP

LP–Proto

Total

Bangle

22

12

28

12

32

4

110

Bell

—

—

—

1

3

2

6

Adze/axe

1

—

—

—

2

2

5

Blade

1

1

4

3

12

1

22

Point

3

1

2

2

7

—

15

Miscellaneous

1

—

2

—

3

1

7

Wire/Rod

26

6

21

8

55

1

117

Flat

30

6

14

10

42

12

114

Amorphous

86

28

38

23

65

3

243

Total

170

54

109

59

221

26

639

% that are tools

3.5%

3.7%

7.3%

8.5%

10.9%

15.4%

Tool

Note: EP = Early Period; EP–MP = Early Period to Middle Period; MP = Middle Period; MP–LP = Middle Period to Late Period; LP = Late Period; LP–Proto = Late Period to Protohistoric Period.

38

2B: THE METALS AND RELATED EVIDENCE

the collection, and the most common find among personal ornaments. Within the class bangles, there is a sufficient number and variation in morphology to propose a typology. Published classification schemes for prehistoric bangles from Thailand are found in Pilditch (1993) and Chang (1998, 2001). Working with ornaments of shell, stone, and bone excavated at the coastal site of Khok Phanom Di, Pilditch set up a typology of twelve basic styles. The styles were based on cross section, size, and proportions. Designed to be applicable to bangles made of shell, stone, and bone, it also aimed to establish a universal bangle typology for Southeast Asia. The ornaments excavated at the coastal site of Nong Nor were also classified according to a revised and expanded version of the Pilditch typological scheme, with 21 basic styles (Chang 1998). Since Khok Phanom Di contained no ornaments of metal and Nong Nor did, it was necessary for Chang to extend Pilditch’s scheme to encompass bangles made of copper-base metal as well as additional configurations of shell bangles (Chang 1998, 2001). Chang’s (2001) discussion, which incorporated bangles from Ban Lum Khao (see also Chang 2004) and Noen-U-Loke and expanded Pilditch’s scheme further with a total of 29 bangle styles, ultimately rejected the usefulness of Pilditch’s subtypes and reduced the role of ratios and dimensional criteria. The cross section of the bangle shaft, which both Chang and Pilditch called “radial section,” is the primary criterion that was consistently found useful in developing a bangle classification scheme. The four-site collection examined here contains many more metal bangles than those recovered from Nong Nor and offers a greater diversity of cross sections and variations in closure type. Among Khok Phanom Di and Nong Nor bangles, the high proportion made from shell influenced the formal variations recognized by the Pilditch and Chang typologies. Much of that variation is not pertinent to metal bangle variation at Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang. Differences in bangle morphologies in prehistoric northern northeast Thailand versus coastal Thailand likely reflect differences in the parent materials. The plasticity and working properties of shell, stone, bone, clay, and metal will govern the range of achievable shapes. Cast metal, because it is poured as a liquid, has the greatest potential among all these materials for modeling precise and complex forms.

Because of these differences and limited overlap in the bangle shapes between shell, stone, clay, and metal bangles, and between the bangle shapes found at Khok Phanom Di, Nong Nor, and Ban Chiang, a new bangle typology was created for this volume, one based on variation solely in the metal bangles (including anklets and rings) excavated just from the four northeast Thailand sites under study here. Like previous typologies, the basis of the bangle types is cross section shape and size, but here subtypes are defined for variations in kinds of closure, i.e., whether the bangle is a complete circle, a C-shaped bangle with a gap between the ends, etc. An important objective is to be able to assign bangle fragments, with or without known closures, to cross-section types. Therefore, bangle fragments almost always can be assigned to a cross-section type, no matter how incomplete the fragment available, but more complete bangles can be specified to closure type, i.e., subtype, as well. Although dimensions and ratios of the sort used by Pilditch (1993) are avoided in the typology used in this volume, exceptions include differentiating the cross sections of Type A from Type B by size and Type G from Type N by proportional criteria (see Table 3.4). Metric variation can be separately evaluated within formal types, but given that the bangles are in a range of sizes with no clear divisions, the arbitrary subdivision of types by size is premature. It is important to reemphasize that no rigid judgment as to function is implied by the term “bangle.” Most of the artifacts classified as bangles were undoubtedly used as personal jewelry—bracelets, anklets, rings, and necklaces—given that many were found circling the limbs of skeletons in burials. Unlike preceding typologies, anklets are not differentiated in the typology from bracelets because even if some bangle morphologies have only been found so far on ankles or on arms, sample sizes are too small to assume that they will not in the future be found on both limbs. Bangles excavated outside of in situ graves provide no evidence for the body parts, if any, they were intended to adorn. Also, from a manufacturing point of view, anklets and bracelets have similar design characteristics, represent equivalent tasks, and were likely made in the same way. In addition, not all bangles were necessarily intended to be worn directly on the body. Some bangles, such as BC 2155/702 (Fig. 3.3f ), a small ring

CLASSIFICATION OF METAL ARTIFACTS

with overlapping ends, could also be an ornament to decorate another artifact. Nor do all personal ornaments fall within the bangle class: many pieces of wire, some with slight curvature, were parts of necklaces, judging from the position of several examples in one grave, and are classified as wire/rod based on morphology. At least 110 metal bangles and bangle fragments were recovered from the excavations at Ban Chiang, Ban Phak Top, Ban Tong, and Don Klang. These 110 metal bangles provide the basis for the detailed typology presented below. Bangles fused together by corrosion, such as BC 693A–D/1203A (Fig. 3.3a, Color Fig. 3.24), and BC 679A–B/1701 (Fig. 3.4b), are treated as separate artifacts if the number of separate bangles can be determined. The words “at least” are used in cases such as BCES 533/1601 (Fig. 3.8c), in which several iron bangles are found fused and broken but the number of separate bangles is unclear. In this case, the bangles are treated as a single artifact. The typology presented here is not intended to be comprehensive for the prehistoric period in the northern northeast Thailand. Although metal bangles from Ban Na Di (Higham and Kijngam 1984:132–135) show much overlap in morphology with the bangles from Ban Chiang, those types peculiar to Ban Na Di can be incorporated easily into a larger regional metal bangle typology in future efforts. Metal bangles purportedly from Ban Chiang cultural tradition sites in private collections or from other unprovenienced contexts show variations that, if excavated from in situ contexts, may also expand the typology used here.

Terminology To discuss the bangles in a systematic manner, the following terms are used (Fig. 3.1 illustrates many of these terms). Shaft configuration is the body of the bangle as it curves around the finger, wrist, ankle, or neck. Disk-shaped bangle has a shaft configuration like a plate with a hole in the middle through which the body part is inserted. Cuff bangles have shaft configurations that resemble a wide tube encircling the body part.

39

Shaft closure includes such forms as closed circle, C-shaped, overlapping, or spiral. “Spiral bangle” is a special variety of shaft closure similar to the category of the overlapping end bangle, but where the overlap is more than 50% of the circumference. Opening refers to the outline of the interior hole for wrist, finger, neck, or ankle; it is usually circular or oval. Smooth surface means that there is no decoration, either of incising or of form; the shaft’s surface is smooth and plain. Inside surface or edge refers to the surface or edge of the shaft that would rest against the skin if the bangle were being worn. Outside surface or edge refers to the surface or edge of the shaft furthest away from the skin if the bangle were being worn. Top/bottom surface or edge refers to the surfaces of the shaft perpendicular to the wrist or ankle. Shaft height refers to the top-bottom measurement of the shaft. Shaft width refers to the measurement from the inside edge to the outside edge. Interior diameter refers to the diameter of the inside opening, the space that the body part would occupy. Bracelets are bangles found in situ around the wrist of a skeleton. Anklets are found in situ around the ankles of a skeleton. “Bracelet” and “anklet” are used in the text instead of bangle when the context of a bangle is being emphasized. Flange is a ridge that projects laterally from the body of the bangle, used to refer to the horizontal bar in a T-section bangle (Figs. 3.1, 3.2E, 3.6a). The height of the flange is less than the height of the bangle. The definition used here for flange is based on its likely etymological source in the French flanche, meaning spreading out or widening; thus, the portion of relevant bangles comprising the flange in this discussion differs from Chang (2001:31, fig. 4.1).

40

2B: THE METALS AND RELATED EVIDENCE

Table 3.4  Metal Bangle Types Recovered, All Sites Combined

Parent Type

Cross Section of Shaft

Subtypes (based on shaft closures)

Chang’s Related Stylea

A

round or slightly oval cross section 1 mm. It is too short a fragment to estimate interior diameter.

Three bangle fragments are either missing or were wholly mounted in the metallographic mount before their cross sections were ascertained. The original excavators classified these artifacts as bangles. These are considered of unknown cross section and type.

type m: elaborated form (fig. 3.6q) Type M, with a V-shape cross section, has only one fragmentary copper-base representative in the collection, BC 2160/276, which came from the general soil matrix. It has an interior diameter of 4 cm. No decoration is visible, but the surface is corroded.

type n: elaborated form (fig. 3.6r) Type N has only one representative, an intact N-1. This is a complete cuff bracelet, BCES 532a/1601, fully closed and from BCES Burial 26. This is a remarkable specimen—a copper-base flat, thin cuff bangle marked with four parallel horizontal grooves and small copper-alloy bosses. It was surrounded by two Type A iron bangles (BCES 532B–C/1601, Fig. 3.8g, Color Fig. 3.28) fused together by corrosion. The inner diameter of the copper-base bracelet is 4.5 cm.

type o (fig. 3.8k) This type contains bangle fragments that are too corroded or distorted to be able to ascertain with any

Iron versus Copper-base Metal Bangles Because of the different material properties of iron and copper-base, manufacturing artifacts in the two metals requires two quite different complex technological systems, as discussed in TAM 2A, chapter 7. Copper-base metal can be cast; iron in most prehistoric contexts was forged. Copper-base bangles show a greater range of types than iron bangles, partly because iron corrosion is much more likely to distort the original cross section and reduce it to a simple roundish shape and partly because the shapes of iron objects would be confined to those that were forgeable with a hammer. All the types have representatives in copper-base. Because most of the copper-base bangles were probably cast with the lost wax process, potentially they could take a much wider range of forms than the iron bangles. Some forms such as Type K would be difficult to create with hammering, and, given that one side of the Type K scalloped bangles is flat, they seem likely to have been cast in bivalve molds where one mold valve is flat. As far as can be ascertained after centuries of corrosion, the iron bangles were made in some of the plainer forms also rendered in copper-base, perhaps imitating the copper-base forms but in a new material. Some combinations of types and closures are unique to iron bangles, however. The only representatives of G-4 (Fig. 3.8h–i) are of iron. On the other hand, new copper-base bangle types occur throughout the sequence, showing that copper-base

47

CLASSIFICATION OF METAL ARTIFACTS

bangle casting was subject to ongoing stylistic innovation. Iron is only found in Types A, G, and I, all of which are cross-section types of a simple shape that is readily forgeable, plus the irregular Type O. As can be seen in Table 3.6, bangles from Ban Chiang provide most of the evidence for bangle type variation in the collection. All the bangle types described in the typology were recovered from either the BC or the BCES locale at Ban Chiang. No bangle types are unique to Ban Phak Top, Ban Tong, or Don Klang, although the sample of bangles from these three sites is too small to be able to generalize on this topic. Overall, a common tradition of bangle morphology appears to be shared among the four sites. Simple cross sections of A and H appear at Ban Chiang and the other three sites, especially from Early Period deposits at Ban Tong and Ban Phak Top. Only Don Klang shows some variation,

and its bangles all come from the Late Period, with examples of wedge-shaped (Type I), crescent-shaped (Type F), and hollow (Type L) cross sections in addition to Type A. On the other hand, nearby Ban Na Di, while showing considerable overlap in metal bangle repertoire with Ban Chiang, does have some different shapes from those defined here (although the differences are small (Higham and Kijngam 1984:132– 134, 145). Intersite variation in bangle shapes may become clearer as more metal bangles are recovered from secure contexts in this region.

Bells The bells recovered from prehistoric contexts at Ban Chiang and Don Klang closely resemble rattles

Table 3.6  Bangle Types by Site/Locale

Parent Type

BC

BCES

A

18

37

B

—

C

Ban Phak Top

Ban Tong

Don Klang

Total

3

3

6

67

3

—

—

—

3

1

—

—

—

—

1

D

5

—

—

—

—

5

E

—

1

—

—

—

1

F

—

4

—

—

1

5

G

—

4

—

—

—

4

H

—

3

—

1

—

4

I

2

1

—

—

1

4

J

—

1

—

—

—

1

K

5

—

—

—

—

5

L

1

—

—

—

1

2

M

1

—

—

—

—

1

N

—

1

—

—

—

1

O

1

2

—

—

—

3

Unknown

—

1

1

—

1

3

Total

34

58

4

4

10

110

Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975.

48

2B: THE METALS AND RELATED EVIDENCE

or jingle bells, in the sense that sound is made by a loose, unattached pellet knocking around inside a hollow, perforated sphere. The six excavated bells, all copper-base metal, are hollow, thin-walled spheroids with a slit at the bottom; one still retains its bronze pellet (White 1982:81). They are small, less than 2 cm long. Three complete specimens and two fragmentary bells are equipped with loops; apparently, they were designed to be strung on a cord or slender bangle. One is too fragmentary to tell if it originally had a loop. On all the bells, whenever a substantial portion of the body of the bell or rattle is visible, the body surface has spiral or concentric ring grooves. There are at least two stylistic variants. Most examples have ring grooves parallel to and on either side of the split. One, BCES 162/205 (Fig. 3.9b, Color Fig. 3.25), has ring grooves parallel to the split on both sides of the split and ring grooves perpendicular to the split between the split and the loop. The bells appear to be confined to the later prehistoric phases of the iron period. One (BCES 725/2511, Fig. 3.9d, Color Fig. 3.25) came from Middle Period–Late Period deposits, three (BCES 162/205, Fig. 3.9b, Color Fig. 3.25; BCES 254/604A, Fig. 3.9c, Color Fig. 3.25; DK 211/380, Fig. 3.9e) came from the Late Period, and two (BC 608/535, Fig. 3.9a; DK 341/285, Fig. 3.9f ) came from the Late Period–Protohistoric. All six were excavated from the general soil matrix. Similar bells are still made by the lost wax process in the Philippines where the bells and their curvilinear decoration are formed by wax “wire” (Newman 1977:219; White 1982:81).

Adze/axes One set of metal implements (Fig. 3.10a–e) shares a similar design, a flattened or sharpened blade that extends out in a straight line from a socket, with the edge of the blade perpendicular to the axis of the socket. The splay of the blade is usually symmetrical. The full name of this artifact class is “adze/axe/ tiller” as some specimens may have been used in soil cultivation. However, the abbreviated and less cumbersome “adze/axe” is used as the class name in this volume. In the end, the class name “adze/axe” in this monograph is used as a morphological more than a functional concept.

In the archaeological literature of prehistoric northern northeast Thailand to date, a variety of terms have been used for metal artifacts with attributes similar to those found here: axes, adzes, hoes, digging stick tips, picks, and digging tools. If the hafts had survived, a functionally appropriate term could be applied to some individual specimens, but in most cases, individual implements could have been hafted in several different ways and, thus, may have had a variety of different functions. Recognizing that the terminology did not imply function, at Non Nok Tha, Bayard grouped all similar implements into five types of bronze “axes” (Bayard 1980:192, 214) with blades displaying a variety of shapes and cutting edges showing a variety of curvatures, lengths, and splays. Wilen (1989:43–46) found at Non Pa Kluay a related range of shapes in iron artifacts that he termed narrow bladed “hoes,” “fan-shaped” axes, and “T-shaped…picks.” In the terminology used in this volume, all these artifacts would be grouped in the class “adze/axes” in that they share a common positioning of the blade and cutting edge relative to the hafting element. However, it is important to realize that the hafting of these artifacts relative to a handle, and, hence, whether an artifact functioned as an axe (head hafted perpendicular to the handle, cutting edge parallel to axis of handle), an adze or hoe (head hafted perpendicular to the handle, cutting edge in plane perpendicular to axis of handle), or a digging stick or similar chisel-style implement (hafting element aligned with and extending from the haft with the cutting edge at the end of the head perpendicular to the axis of the handle) is usually unknown. Four relatively complete socketed adze/axes were recovered from two of the five sites/locales. (In one additional heavily corroded piece from Ban Chiang, the tip of the blade was preserved [Fig. 3.10b], making a total of five possible adze/axes.) Two of the more complete adze/axes came from Ban Chiang and two came from Don Klang. One adze/axe is of tin bronze; the others in this class are of iron. They take three different forms. The bronze adze/axe (BC 694/1203A, Fig. 3.10a, Color Fig. 3.24) has a long socket with an elliptical cross section and a splayed flat blade. The blade is described as “fan-shaped.” This subtype is somewhat similar to Type 3 at Non Nok Tha (Bayard 1980:192, 214), although it is too early to suggest that adze/axe forms so far excavated from prehistoric contexts in northeast Thailand had standardized shapes.

49

CLASSIFICATION OF METAL ARTIFACTS

Its position in BC Burial 23, an upper Early Period burial, suggests that this particular artifact had been hafted with the cutting edge perpendicular to and to one side of the handle and, hence, functioned as an adze (Figs. 3.10a, 3.11; see Fig. 6.14b for photograph of burial context). The other fairly complete adze/axe from Ban Chiang (BC 1101A/336, Fig. 3.10c) is of iron and has a socket that is round in cross section and a blade that is no wider than the diameter of the socket—it is designated “narrow-blade adze/axe.” This adze/axe is similar to Wilen’s “hoe” (1989:44) at Non Pa Kluay, and a digging stick tip or hoe from Ban Na Di (Higham and Kijngam 1984:145, fig. 3-26a). This narrow-blade adze/axe was recovered from the Late Period–Protohistoric general soil matrix. It could equally be a digging stick tip. This may also be true of the blade tip fragment (BC 1100/141, Fig. 3.10b), also from the general soil matrix and the Late Period–Protohistoric. The preserved blade tip fans out more than the blade of BC 1101A/336, but not enough to prevent it being used as a hoe or other tilling implement. The two iron adze/axes from Don Klang (DK 283/445, Fig. 3.10d; and DK 302/457, Fig. 3.10e) resemble each other closely, with tapering round sockets and two flaring curved wings on the blades, so they are called “winged adze/axes.” They both came from a Late Period burial, DK Burial 8. Their curving T-shaped blades are reminiscent of a bronze “axe” (Type 2) from Non Nok Tha and iron “picks” from Non Pa Kluay (Wilen 1989:45). Corrosion was too advanced on the iron specimens to be able to detect

any wear. They may have been hafted with the socket in alignment with rather than perpendicular to the handle. At least one of the winged implements found in DK Burial 8 lay flat and its socket was aligned with the axis of the skeleton. If the haft, presumably wooden, was interred while fastened into the iron artifact, the likely implication is that haft and socket were in alignment along the same axis and thus the implement would have been hafted at the tip of the handle. The mechanics of using such a tool imply a thrusting motion rather than a swinging action. Moreover, the proportions and angle of the “wings” of the implement do not suggest the artifact functioned like a modern-day axe, adze, or pick. The tool may have been used with a linear thrusting action.

Blades The class “blades” comprises elongate flattish metal artifacts whose working edge appears to have been along a longitudinal side and aligned with the axis of the haft, even if it is not always clear, due to corrosion, which side of the blade was the working edge. Variations are defined based on the shape of the edge, shape of the overall object, and the presence, position, and shape of the hafting element. The 22 blades and blade fragments are divided into four types: lunate, curved, straight, and unclassified (Figs. 3.12–3.13 and Appendix A, Table A.1). Blades were recovered from all sites/locales except Ban Phak Top (Table 3.7).

Table 3.7  Metal Blade Types by Site/Locale and Period

Type

BC

BCES

BT

DK

Total

Period

Lunate

1

2

—

—

3

MP, MP–LP, LP

Curved

—

3

—

1

4

LP

Straight

1

4

—

—

5

MP, MP–LP

Unclassified

1

7

1

1

10

Total

3

16

1

2

22

EP to LP–Proto

Note: All blades are iron unless noted otherwise. BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975; BT = Ban Tong; DK = Don Klang; EP = Early Period; MP = Middle Period; MP–LP = Middle Period to Late Period; LP = Late Period; LP–Proto = Late Period to Protohistoric Period.

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2B: THE METALS AND RELATED EVIDENCE

The lunate blade (Fig. 3.13a–c) appears to be a distinct type that also has comparable representatives, termed lunate knives, at Ban Na Di (Higham and Kijngam 1984:146). Lunate blades, all of which are iron, have straight or slightly curved blades of a crescent-like shape with projecting horns at each end. Intact examples range in length from 6.9 cm to 8.7 cm. There appears to be no tang or socket, but they may have been hafted along one of the longitudinal sides opposite the working edge. Higham and Kijngam (1984:123) suggested that lunate blades from Ban Na Di resemble Han period Chinese handheld harvesting knives, but the resemblance is not strong. Hand-held harvesting knives where the metal blade is encased in wooden or bamboo handles are recorded in the Southeast Asian ethnographic record (e.g., Simana 2003:22 [pictures], 29 [English text]). Curved blades differ from lunate blades in that they are larger (intact examples range in length from 11.5 cm to 36.5 cm), were probably hafted at one end, and the curvature is more variable and usually more pronounced. They can show the smooth curve suggestive of a sickle (DK 255A/400, Fig. 3.12g) or a sharper, almost 90° angle (BCES 2004/2669, Fig. 3.12f ). Three out of the four curved blades have tangs that suggest how they were fitted into hafts. The hafting area of the fourth curved blade is missing. The two largest metal objects in the four-site collection are the two curved blades, both of iron. Pieces of wood, probably from the haft, still clung to the tang of BCES 2004/2669 at the time of excavation. DK 255A/400, a burial find, was paired with a flat, unclassified blade (DK 255B/400, Fig. 3.12h) in the grave in such a way as to suggest that they were part of the same or related tool or tools (Figs. 3.12h, 3.14). The blade of the “straight” type extends in a straight line from the presumed hafted portion and two of the five examples in the study corpus have a tang that would have fit into a wooden haft like a knife. A similar tanged, straight knife was found at Ban Na Di (Higham and Kijngam 1984:145, fig. 3-26c). The ten unclassified blades are blade fragments or blade tips that show no curvature and give no information as to the method of hafting. Only three of the 22 blades are of copper-base metal, all in the unclassified category, and they came from the Early Period, the Early Period–Middle Period, and the Middle Period. Thus, all the typological

variation occurs in blades made of iron. In the Middle Period, blades start to be made of iron instead of copper-base metal, and after the Middle Period all blades are of iron. Curved blades are the most tightly restricted in time; all four came from the Late Period. Ten blades, all iron, were recovered from burials (one burial at BC, four burials at BCES, and one burial at Don Klang, see Appendix A.1). Grave good blades include all four types. Only five of the 22 blades, all iron, show clear evidence for how they were hafted, and all of these were tanged. Most blades (72.7%) come from BCES, with all types and periods represented. Blades are disproportionately represented at BCES, since only 34.1% (218/639) of all the metal artifacts from the study collection came from BCES. With only 22 blades in the total collection, though, this disproportion may be by chance.

Points The class “points” includes a variety of shapes and sizes (Figs. 3.15–3.18). Traits in common are that: (1) they all come to a sharp point opposite the hafting end; (2) they were all likely hafted and the hafting elements when present are tangs or sockets; and (3) they appear to be designed to pierce a surface when projected or thrust into something. The class is subdivided into four types based on size and overall morphology: (1) small points (Fig. 3.15a–d); (2) spear points (Figs. 3.16a–c, 3.17a–d); (3) spikes (Fig. 3.17e–f ); and (4) unclassified (Fig. 3.18a–b). Although types imply function, no specific function is assumed for any type. Some types have subtypes based on hafting element: socketed, tanged, or unknown hafting. Appendix A, Table A.2 lists the individual descriptions of the points. The four small points (Fig. 3.15a–d) are all tanged and of copper-base metal. These are similar to arrowheads from Ban Na Di (Higham and Kijngam 1984:98). There is, however, no direct evidence for bow and arrow technology, although the pellet bow has been assumed to be the source of projectile energy for the baked clay pellets frequently found at these sites. These small points might also have been hafted onto narrow shafts used as hand-held lances, perhaps for fishing. All these small copper-base points came from the Early Period through the Middle Period.

CLASSIFICATION OF METAL ARTIFACTS

Spear points (Figs. 3.16a–c, 3.17a–d) can be made of copper-base alone, iron alone, or with iron blades and copper-base sockets. Whatever the material, all the spear points have a similar shape. The spear point form has a long blade with a flat cross section that broadens out from the hafting element, either sockets or tangs, and then narrows into a point. Sometimes a midrib can be seen in the centerline of the blade (Fig. 3.16a–c); other examples have a thickened midsection. Among socketed forms, the earliest spear point (BCES 762/2834, Fig. 3.16a, Color Fig. 3.30), from the Early Period, is of copper-base, followed by bimetallic (iron head and copper-base socket) forms (Fig. 3.16b–c, Color Fig. 3.29) in the Middle Period. Forms in iron (Fig. 3.17a–d) appeared in the Middle Period–Late Period and Late Period. The single tanged iron spear point (BCES 426B/1222, Fig. 3.17d) is as long as the socketed iron spear points, but it is heavily corroded and its original form can only be approximated. On the whole, socketing was preferred for the hafting of spear points; five of the points were socketed and only two tanged. The two tanged spear points are of iron and date to the Late Period, but the socketed forms are both iron and copper-base and came from the Early Period, Middle Period, and Late Period. The spike form, of which there are two iron examples (Fig. 3.17e–f ), has the socket extending nearly to the end of the sharp point. The shape is conical. The cross section remains circular through the length of the artifact, unlike the spear point. There are two unclassified points (Fig. 3.18a–b). The first is a socket with an attached rod-like point. Another long rod found in association may have once been an extension of the rod. The second is a portion of an iron flat blade with a thickened center suggesting a midrib. The blade narrows to a point and resembles the blade portion of a socketed point. The socketed points are some of the most impressive metal artifacts recovered from the Ban Chiang area sites. One copper-base metal socketed spear point (BCES 762/2834, Fig. 3.16a, Color Fig. 3.30) was cast as a single piece, probably in a bivalve mold (Stech and Maddin 1988:165) and remains substantially intact, with a blade that flares out to 3.9 cm wide and an original length of 15.5 cm. (Measurements are of the bent blade plus socket; had the blade not been bent the total length would have

51

been approximately 16 cm.) The point of the blade had been bent back before interment, apparently deliberately, perhaps to “kill” the blade for its inclusion as a grave good with BCES Burial 76, a flexed Early Period burial. Also excavated from graves were two bimetallic points (BCES 548/1582, Fig. 3.16b, Color Fig. 3.29; BCES 573/1813, Fig. 3.16c, Color Fig. 3.29) that came from the Middle Period. These points are composed of an iron blade and a copper-base metal socket. These are among the earliest iron implements found in Southeast Asia, and the low nickel content indicates that they were of smelted iron (Stech and Maddin 1988:166) rather than meteoritic iron. BCES 548/1582 retains only a portion of its blade, but BCES 573/1813 is substantially intact. The form of the iron blade in the bimetallic point is different from the bronze socketed point BCES 762/2834 (Fig. 3.16a and Color Fig. 3.30), even though both have a midrib. The blade of BCES 573/1813 is much longer and slimmer, and the total length of the artifact is 28.7 cm and 3.6 cm at the widest part of the blade. The bronze sockets were cast onto the already shaped iron blades. A copper-base socket with just the nub of its iron point showing (BT 923) was recovered as a surface find from Ban Tong. Even though most of the iron blade is missing, the size and shape of the Ban Tong socket are very similar to the sockets of the Ban Chiang bimetallic spear points. It is possible that these artifacts were imports; Higham (2002:190) noted that they are very similar to bimetallic points found in Dong Son sites in Vietnam. The distribution of the points in time, space, and context is presented in Table 3.8 and Appendix A, Table A.2. Over time, a similar pattern as with the blades can be seen here with regard to metal type. Copper-base metals were used for the points in the Early and Middle Periods; iron started to be used in the Middle Period, and copper-base points disappeared in the Late Period. Again, more (73.3%) of these tools were excavated at BCES than at the other sites/locales. Seven of the points, or 46.7% of the total, came from burials. The grave good points include one tanged iron spear point, two bimetallic socketed spear points, one copper and one iron socketed spear point, one socketed iron spike, and one unclassified iron point. The points in the burials, unsurprisingly, are the best preserved and most elaborate of the class.

52

2B: THE METALS AND RELATED EVIDENCE

Table 3.8  Distribution of Metal Points by Site/Locale and Period

Type or Subtype

BC

BCES

BPT

BT

Total

Period

Small point, tanged, Cu

1

2

—

1

4

EP, EP–MP, MP–LP

Spear point, socketed, Cu

—

1

—

—

1

EP

Spear point, socketed, bimetallic

—

2

—

—

2

MP

Spear point, socketed, Fe

1

1

1

—

3

MP–LP, LP

Spear point, tanged, Fe

—

1

—

—

1

LP

Spike, Fe

—

2

—

—

2

MP–LP, LP

Unclassified point, socketed, Fe

—

1

—

—

1

LP

Unclassified point, Fe

—

1

—

—

1

LP

Total

2

11

1

1

15

Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975; BPT = Ban Phak Top; BT = Ban Tong; Cu = copper-base; Fe = iron; EP = Early Period; EP–MP = Early Period to Middle Period; MP = Middle Period; MP–LP = Middle Period to Late Period; LP = Late Period.

Despite the small sample size, it may be noteworthy that all the small points are tanged, and all are of copper-base metal. All but one of the spear points have socketed hafts.

Miscellaneous Metal Artifacts The seven miscellaneous metal artifacts (five are illustrated in Fig. 3.19a–e) include four iron socket-like or cylindrical artifacts, one copper-base metal hook, one bronze knob that may be a bangle adorno, and one large solid iron ball with a cleft in one side (Table 3.9). The iron sockets could have been for points, adze/axes, or blades. The iron ball (DK 256/400, Fig. 3.19e) has a linear cleft on one side that appears to be deliberately made and resembles somewhat the slit found in the small copper-base metal bells, though the ball is solid. Pigott and Marder (1984:283) termed this object a “bell,” but as it is solid, lacking a hollow cavity for a clapper, here the object is classed as a ball. The ball is much larger than the copper-base bells, with a diameter of 4.1 cm and a weight of 68.6 g. No decoration can be seen on the corroded surface. Its function is unknown, but it came from the Late Period and was found in a burial

along with two iron blades. All other miscellaneous artifacts came from the general soil matrix. Very like a fishhook, BT 890/1696 (Fig. 3.19b) has a pointed, upturned tip and an eye in the end opposite the hook end. It is 4.1 cm long, of copper-base metal, and came from the Early Period general soil matrix. Similar hooks were recovered from Ban Na Di (Higham and Kijngam 1984:135) and Non Pa Kluay (Wilen 1989:41). The function of the other copper-base miscellaneous artifact is not clear. The knob, known by elemental analysis to be a high-tin bronze (see Chapter 4), is similar in shape to adornos known from unprovenienced Ban Chiang area copper-base bangles.

The Question of Hafting The implements in this collection can be divided into three hafting groups: those that were tanged, those that were socketed, and those for which there is no information. Clearly the knowledge of how to make both sockets and tangs was available from the Early Period to the Protohistoric in this area. The choice between the two did not depend on available expertise, but appears to have been a deliberate decision that took advantage of the different performance

53

CLASSIFICATION OF METAL ARTIFACTS

Table 3.9  Miscellaneous Metal Artifacts

Description

Length or Max. dim.

Context

Period

Artifact ID

Figure

Cu knob

1.3

gsm

LP

BC 2207/355

3.19a

Cu hook

4.1

gsm

EP

BT 890/1696

3.19b

Fe socket?

3.7

gsm

MP

BCES 819/2734

Fe socket

2

gsm

LP–Proto

BC 1101B/336

3.19c

Fe socket

3.1

gsm

LP

BCES 1109/251

3.19d

Fe socket

4.1

gsm

MP

BC 1107/487

Fe ball

4.1

gg: DK B.5

LP

DK 256/400

3.19e

Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975; BT = Ban Tong; DK = Don Klang; Max. dim. = maximum dimension; Cu = copper-base; Fe = iron; gsm = general soil matrix; gg = grave good; B. = Burial; EP = Early Period; MP = Middle Period; LP = Late Period; LP–Proto = Late Period to Protohistoric Period.

characteristics of the two methods. Neither did it depend on the material. Small copper-base points that have tipped slender projectiles are tanged, but six of the seven iron or bimetallic spear points, larger and presumably designed to endure stronger and sharper forces, are socketed. On the other hand, the straight and curved blades for which there is hafting evidence are of iron, and all are tanged. All four adze/axes, one of copper-base and three of iron, are socketed. As a rule, then, one can hypothesize that through the bronze and iron periods, when an implement was designed to endure strong shocks, it was socketed, and if intended for cutting or light hunting, it was tanged. A modern analogy would be with present-day axes and knives; axes are hafted with a wooden handle through a shaft hole, and modern knives are still tanged. This does not mean that every adze/axe, spear point, or blade in the collection was intended for actual use, but the particular hafting style had become incorporated into the definition of the implement and was retained, even when the implement was intended for burial or other non-utilitarian use.

Wire/Rods One hundred seventeen metal artifacts are classified as wire/rod (Table 3.10, Figs. 3.20a–l, 3.21a–t). Of these, 104 are of copper-base metal

and 13 are of iron. Wire/rods are bar-like objects, usually though not always with a round cross section, and are differentiated from bangles by being either straight or nearly so, or are bent in a way unlike a bangle’s smooth continuous curve. With small pieces, though, this distinction can be somewhat arbitrary. Wires (Fig. 3.20a–l) are differentiated from rods (Fig. 3.21a–t) based on diameter, with 0.4 cm as the dividing point. When comparing quantities of wire/rods in the various sites, it is important to note that some artifacts given a single artifact number are, in fact, comprised of two or more pieces that are assumed to have once composed a single artifact. An extreme example of this is BC 2208/0918 (Fig. 3.20c), which has over fifty small broken pieces and crumbs found gathered together next to the neck of a skeleton of a small child, BC Burial 14. This was assumed by the excavators to have been a single necklace. Because it is possible that multiple pieces assigned to a single artifact are pieces of more than one artifact, the exact numbers found in the following tables should be treated as estimates. Wire/rod pieces are divided into four general types (Table 3.11): A, rods (diameter ≥0.4 cm) with round cross sections; B, rods with rectangular, D-shaped, or flattened oval cross sections; C, miscellaneous bits of wire (diameter between 0.15 cm and 0.39 cm) with round cross sections; D, very fine wire

54

2B: THE METALS AND RELATED EVIDENCE

Table 3.10  Distribution of Metal Wire/Rods by Site/Locale

Cu

Fe

% of Total Wire/ Rod Collection from Each Site

BC

13

4

14.5 (17/117)

9.2 (17/185)

BCES

13

6

16.2 (19/117)

8.7 (19/219)

BPT

1

1

1.7 (2/117)

BT

31

—

26.5 (31/117)

26.7 (31/116)

DK

46

2

41.0 (48/117)

47.0 (48/102)

104

13

Site/Locale

Total

% of Wire/Rods in Each Site’s Total Metal Artifacts

11.1 (2/18)

Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975; BPT = Ban Phak Top; BT = Ban Tong; DK = Don Klang; Cu = copper-base; Fe = iron.

Table 3.11  Metal Wire/Rod Types by Site/Locale

Type

BC

BCES

BPT

BT

DK

Total

Cu

Fe

Cu

Fe

Cua

Fe

Cu

Fe

Cu

Fe

Cu

Fe

A

5

2

5

3

—

—

4

—

1

1

15

6

B

1

—

2

3

—

—

1

—

1

1

5

4

C

4

2

6

—

—

1

20

—

9

—

39

3

D

3

—

—

—

—

—

6

—

35

—

44

—

13

4

13

6

0

1

31

—

46

2

103a

13

Total

Note: BC = Ban Chiang 1974; BCES = Ban Chiang Eastern Soi 1975; BPT = Ban Phak Top; BT = Ban Tong; DK = Don Klang; Cu = copper-base; Fe = iron. aThe type of one copper-base wire/rod from BPT could not be determined and is not included in this table.

(diameter