Grow-your-own Crystals 1880592193, 9781880592199

Citation preview

by Carol Benanti Illustrated by Earl Dickens and Gary Lessord

© Copyright 1993 Pace Products, Inc. All rights reserved. No part of this publication may be reproduced, stored on a retrieval system, or transmitted, by any means or in any form, either electronic, photocopying, recording or otherwise, without the permission of Pace Products, Inc. Apopka, Florida 32703. Printed in U.S.A. ISBN 1-880592-19-3 10 987654321

PACE PRODUCTS, INC. FLORIDA

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Introduction What’s in this Kit? What is a Crystal? How Does a Crystal Grow? Crystallization in Action What Really Happened? Crystals from the Earth Crystal Gems Identifying Crystals Crystal Shapes The Colors of Crystals Reflection and Refraction What is Cleavage? Crystal Surprises A World of Crystals ■ Crystal Experiments Crystal Experiment Chart

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rystals are all around us. We sprinkle salt crystals on our french fries, and pour sugar crystals in our iced tea. Some crystals fall from the sky. You know these as snowflakes. And others are found deep within the earth. In fact, crystals make up most nonliving things. But what are crystals and how are they formed? And if they aren’t alive, how can they growl Grow Your Own Crystals will give you the answers to these questions and more. You will learn about the different shapes of crystals, how they are affected by light, and the importance of crystals in our everyday lives. You will even grow your own crystals from some special rocks included in this kit. Then, get ready to grow crystals from common everyday household items. The world of crystals begins right here. Just add a cup of curiosity and a few tablespoons of patience!

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mm ora this kit? The best way to understand crystals is to see and touch them. This kit includes many of the things you will need to examine crystals close-up and to learn more about them.

3 «1MI§ Garnet, quartz, and selenite crystals are included in your kit. You will need these for pages 10,12, and 14.

Many crystals are very tiny. The best way to examine these crystals close-up is through a magnifying glass.

DISPLAY Use this tray to store and display the crystals in this kit and other crystals you may find. It can also be used for growing crystals.

These sedimentary rocks have special crystal-growing qualities. You will need them when you get to page 6.

Jlk. STRING

FULL COLOR POSTER Look at and identify 25 beautiful crystals close-up.

You will use the string in the experiment on page 22. 3

is something that cannot be broken down into something more simple, except through nuclear reaction. Water is made from two elements - hydrogen and oxygen. Elements are made from molecules. Molecules are like the bricks used to build a house. The way the bricks are put together will determine what the house will look like. And the way the molecules are arranged determines what type of element will form. These molecules are made from atoms.

If you look closely at a brick house, you will see that the bricks are lined up in patterns. When the molecules and atoms of matter line up like this, the matter is called a crystal, or crystalline. This pattern is called the symmetry of the crystal. In some crystals, this symmetry makes the surfaces of the crystal smooth and flat, like a salt crystal or a diamond, but many crystals have surfaces that are rough and irregular. The study of these crystals is called crystallography, and a person who studies them is called a crystallographer. Metals, like iron and copper, may not look like crystals, but they are because their atoms and molecules have a certain symmetry. Glass may look like a crystal, but it is not, because its atoms and molecules have no symmetry. Actually, glass is molded from silica, which was once a crystal. When the silica is melted, it loses its crystal qualities. One of the most important qualities of crystals is that they actually grow. 4

U eople need food to live and grow. Food goes to the cells in your body where a chemical reaction takes place. This chemical reaction changes the food into things that your body needs to grow. Since these cells are inside your body, you grow from the inside. Crystals grow too. But they grow from the outside. Crystals form from vapors, which are gases, solutions which are liquids, or melts, like molten lava. When pressure, heat, or evaporation occurs, a chemical reaction between certain atoms and molecules can make them join into a cluster. This cluster is called a unit cell, and it is the start of a crystal. As more atoms and molecules are joined together in regular patterns, the crystal grows larger and larger. This process is called crystallization.

If you have ever played in the snow, you’ve already made giant crystals. Snowflakes are crystals of ice. When you make a snowball, you pack more and more snowflakes together. The pressure from your hands makes the snowflakes stick together and your crystals grow larger and larger as you pack more snow on the outside of the ball.

A CRYSTAL GROWS FROM THE OUTSIDE

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ffflffl sure CKISTMMMlW sedimentary rocks found in Southern Utah. Look at them closely through your magnifying glass. What do you see? These rocks are dark gray with bits of white. Can you see any crystals in the rocks? Maybe not yet, but by pouring a special solution over these rocks we can see crystallization in action.

WHAT YOU WILL NEED ♦ 2 crystal-growing rocks (included in this kit) 1 plastic display tray (included in this kit) ♦ white distilled vinegar

Place the rocks in the tray and slowly pour the vinegar over them.

Crystals will start to form on the top and sides of the rocks within 12 hours. Leave them in the dish for up to a week. When all of the vinegar evaporates, the crystals will become very hard. Then you can remove and display them. You can also color the crystals if you like. Just add a drop of food coloring to the vinegar after a couple of days.

Leave about 14" of the top of the rock above the vinegar. This space is very important, because this is where the crystals will begin to grow. 6

J he white bits in the rocks are deposits of calcium carbonate. The vinegar mixes with this calcium carbonate and a chemical reaction begins. As the vinegar evaporates, crystals of aragonite begin to form. Many mineral crystals from the earth form from chemical reactions and evaporation, just like your aragonite crystals did.

Many mineral crystals are also formed by the heat and pressure of the earth. Some minerals, like diamonds and graphite, are made from the same element - carbon. But different amounts of heat and pressure cause different crystals to form. Some mineral crystals, like salt, are so small, that you can hardly see them. And some, like beryl, grow so large that they can weigh several tons. 7

Ml ome crystals grow in solid rocks beneath the moving mountains of the earth. Agate, amethyst, and topaz grow in volcanic rocks near the earth’s surface. Rubies, sapphires and aquamarine grow deeper in the earth’s crust from great heat and pressure. Diamonds grow below the earth’s crust from tremendous heat and pressure. Then they are forced to the surface through volcanic activity.

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CRYSTAL GEMS ^Fhe earth helps form many of the crystals that you see every day. But sometimes as crystals grow, they are pressed against rocks and lose their shape. Other times, they break apart and are rubbed as they tumble along the bottoms of streams and rivers. Rough crystals can be tumbled into smooth shapes to create gem crystals.

AMETHYST Amethyst is a purple quartz crystal which can be tumbled or cut.

RUBY

Rubies are red crystals of the mineral corundum. Most are flat, but they can be cut to enhance their rich color.

EMERALD Emeralds are green crystals formed from the mineral beryl. Many raw emeralds have fractures in them which can be cut away. 9

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'ome crystals are easy to see and some aren’t. Salt crystals . are very small. Look at some salt under a magnifying glass. You can see very tiny cubes. One way to tell the difference between crystals is by their shape. Crystallographers have to examine crystals very carefully when they try to identify them.

FUN HUE

SALT CRYSTALS

We’ve included three different crystals in this kit for you to examine. The dark gray rock is schist with garnet crystals. Look very carefully at this rock through your magnifying glass. Can you find the crystals of garnet growing in the rock?

They look like large brown salt crystals. Salt and garnet crystals both have the same shape. They are both cubes. 10

IA

icube has three dimensions - length, width, and height. If you draw imaginary lines through the center of the crystal showing each dimension, you will notice that each line intersects and is the same length. This is actually the simplest crystal structure called isometric. The imaginary lines are called the axes. A crystal can actually grow in one of seven different shapes isometric, tetragonal, hexagonal, rhombohedral, orthorhombic, monoclinic, or triclinic. Some crystallographers consider the rhombohedral and hexagonal shapes as one, since the axes are the same. The only difference is their symmetry. Lri>

HEXAGONAL: Six-sided, like a snowflake; two axes are equal in length, one axis is longer or shorter

ISOMETRIC (OR CUBIC): A very common crystal shape with three equal main axes, all at right angles

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ORTHORHOMBIC: Three unequal axes, meeting at a center of symmetry

TETRAGONAL: Rectangular, shoebox shape; also has three main axes, but one is unequal to the other two

Three unequal axes; two at right angles and one tilted.

TRICLINIC: Two axes tilted, one upright

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■ Ti nother way experts can tell the difference between crystals is by their color. Some crystals are clear, like a pure diamond, and some can be found in rainbows of color. But trying to identify a crystal by its color can be very confusing. The color of a crystal depends on what kinds of other minerals are mixed with it as it grows. Pure quartz is clear. But tiny bits of iron and manganese can turn a clear quartz into a beautiful purple amethyst. The color may also be affected by changes in the crystal structure. Radioactive elements, like uranium or thorium, can cause these types of changes. These elements can change a clear quartz into smokey quartz.

fUNMlE The clear crystal included in your kit is quartz. Look closely at it through your magnifying glass. Can you see the light shine on it? This is caused by the way light is reflected and refracted. 12

REFRACTION

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U u hen you look in a mirror, you see your reflection. But what are you really seeing? Light bounces off your face and through the glass on the mirror. It hits the shiny silver backing and bounces back through the glass to your eyes. This return of light is called reflection.

But when light passes through some materials, it travels at different speeds. The slowing down or speeding up of light makes it appear to bend. If you place a pencil in a glass of water, the pencil will seem to bend where it meets the surface of the water. Light travels more slowly through water than it does through air. This bending of light is called refraction. Crystals can reflect and refract light depending on their structure. When this happens, beautiful rainbows of color can appear. 13

mm m | f you tear a piece of paper in one direction and then the other, you will notice that one tear is jagged and crooked and one is smooth. This is because the molecules line up better in one direction than in the other. In paper this is called the grain, in crystals it is called cleavage. The cleavage of a crystal creates flat surfaces. Mica splits in one direction to form thin sheets. Some crystals may have more than one cleavage direction. Diamonds split in four directions and will form a pyramid. Quartz has poor cleavage and will break into irregular pieces. Perfect cleavage is found only in crystals, although not all crystals have perfect cleavage. This shows the orderliness of their molecular pattern.

FUN 1ME The final crystal included in the kit is called a selenite rose. It is actually a form of crystal gypsum. Gypsum is the white mineral used to make plaster of paris. Look at it closely through your magnifying glass. Can you see the sparkling bits of selenite crystal? As this crystal grows it can form the shape of a rose.

If you break off a little piece, and examine it under the magnifying glass, you can see its cleavage, and the pieces you broke off look like small crystals. 14

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HP ut now that we know what crystals are, what can they be used for? Many crystals that sparkle and shine are used in jewelry. But some crystals have very unusual qualities. FI EZQm LiOTR! O EFFECT

Calcite crystals can form perfect six-sided rhombohedrons with parallel opposite sides. This special shape causes light to bend through two surfaces. Looking through a calcite crystal, you can see two images. This is called double refraction.

A thin slice of quartz can become charged positively on one side and negatively on the other. This allows an electric current or signal to pass through the quartz and can be used in radios, televisions, and radars. This is called the piezoelectric effect.

This piezoelectric effect is also useful in quartz clocks and watches. When electricity is applied to the quartz crystal plate, it causes it to vibrate. Most crystals vibrate 32,768 times a second. This vibration can be used to keep track of time. Some quartz watches are accurate within one minute a year.

Some watches and calculators also have a liquid crystal display or LCD. Liquid crystal can flow like a liquid, but its molecules are lined up like a crystal. An electric charge can change the pattern of the molecules and make the liquid crystal change color. 15

dually, we use crystals every day. They can be found in almost every field of science and technology. Look below at just some of the things made from crystals. Can you think of some other things that are made out of crystals?

Many household items are made from iron or steel. These include hammers and screwdrivers.

Many of the coins used today and in the past are made from crystals. Pennies are made of copper and zinc crystals, while dimes, quarters, and nickels are made from copper and nickel. In the past gold and silver were common crystals used for coins.

Some of world’s most beautiful crystals are used in jewelry. People love to wear things that glitter and sparkle, like crystals of gold and crystals of diamonds and rubies. 16

The only way to cut a diamond is with another diamond. There are special cutting blades made from diamonds that can do just that.

Crystal lasers can be made with real rubies. A ruby rod amplifies or increases the light from a flash tube. A ruby laser can burn a hole through a piece of steel.

inns Because of the special electrical qualities of quartz, an exact frequency can be created. This frequency is used to tune in radio and television stations.

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SOLAR CELLS

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Pure silicon crystals, similar to quartz, are used to create solar cells that power nearly all man-made satellites and spacecrafts.

ow that we know the basics of crystals we are ready to begin experimenting. We don’t have to journey to the center of the Earth to grow our crystals - we can grow crystals right at home! Most things that are already made up of crystals, like sugar or salt, can grow into crystals. As we noticed earlier, many crystals form through evaporation. Liquids, like water and vinegar, will evaporate into the air. After all the liquid has evaporated, all that are left are solids that were mixed in with the liquid. The simplest way to grow crystals is from a solution. A solution is made by dissolving a solid, like sugar or salt, in a liquid, like water. You can also make a solution by dissolving a liquid in a liquid. Both ways require a constant temperature. Many of the nicest crystals are formed from saturated and supersaturated solutions.

When you dissolve a solid in a liquid you are making a solution. When you dissolve as much solid as the liquid can hold, the solution is called saturated.

If you take that same saturated solution and heat it, the molecules expand and can hold more. The solution is not saturated anymore. When you dissolve more solids in it and it is cooled, the solution becomes supersaturated. Most of the experiments in this book use the principle of saturated and supersaturated solutions to make crystals. 18

NOTE: Adult supervision required. Always have a grown-up helper nearby when doing these experiments!

SETTING UP YOUR LABORATORY Every crystallographer needs a place to work. This will be your laboratory. Your kitchen is perfect. Always gather the things you will need before you start working. That way you will always be sure that you have everything.

BASIC THINGS YOU WILL NEED

TIPS AND WARNINGS 1. Keep your “laboratory” clean at all times. Cover your table with newspaper, and clean up any spills quickly. 2. Handle all solutions CAREFULLY. Keep them away from your eyes and mouth. 3. When using hot water, always have your grown-up lab assistant help you. ALWAYS use pot holders or towels to handle containers with hot water. 4. NEVER put hot water into a glass jar. Use heat resistant jars, or plastic. 5. Keep a chart of the results of your different crystal experiments. It will be fun to learn which crystals grow the quickest! (We've supplied one on page 32.) 19

Pour about lA of a cup of salt into the water and stir until it is dissolved.

♦ REMINDER

You have now made a solution. This is the first step in making a supersaturated solution that your crystals will form from.

Pour the hot water into the pie pan. 20

Keep dissolving more salt into your solution, one tablespoon at a time until no more salt will dissolve. You will be able to see the salt start to stay in the bottom of the pan.

Put your supersaturated solution in a safe place and leave it overnight. Clusters of salt crystals will begin to form by morning. The more water that evaporates, the larger the salt crystals will grow. 21

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WHAT YOU WILL NEED ♦ 2 tbsp. of rock salt (You can find this in your grocery store near the regular table salt. It is used to make ice cream.) ♦ 1 cup very hot tap water + 1 measuring cup + 1 spoon + 1 piece of string ♦ 1 pencil

Tie the string around the pencil and lay the pencil across the top of the cup so that the string is in the water. 22

Stir the rock salt in the cup of hot water until it dissolves.

Put the cup in a bright, sunny spot, like a windowsill.

Leave it alone for a day or two. Check it once a day.

Clusters of crystals will start growing on the string.

jjp_ The longer it sits, the larger the crystals should grow, until all the water has evaporated.

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WHAT YOU WILL NEED + ♦ ♦ ♦ ♦ ;

1 2 1 1 1 1

cup of very hot water cups of sugar pint jar small pan spoon old towel

Stir in a half a cup of sugar until it dissolves. Keep adding a half cup at a time until all the sugar dissolves.

Pour the hot tap water into the pint jar. 24

Wrap a towel around the jar. This will let the solution cool slowly.

Leave the jar in a safe place for two to three days. Clusters of sugar crystals will form on the top and bottom of the jar! Some may form along the sides.

TIP The only way crystals will form, is if the solution cools slowly. Keep the towel wrapped around the warm solution and be patient!

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WHAT YOU WILL NEED Sometimes, inside a cave, water and limestone seep into cracks in the ceiling. As the water evaporates, beautiful crystals form that look like icicles. The crystals growing down from the ceiling are called stalactites, and the crystals growing up from the floor are called stalagmites. Sometimes they meet in the middle!

♦ ♦ ♦ + ♦ ♦ ♦ ♦ ♦

two small jars 1 jar lid 1 strip of old towel, about 1" wide and 2' long 1 measuring cup 1 spoon 3 cups of hot tap water 1 tray lOtbsp. washing soda (Can be found in the laundry detergent section of the grocery store.)

Add 5 tablespoons of washing soda to each jar. Stir the solution well until they dissolve.

Rinse the jars and pour 1 Vi cups of hot tap water into each one. 26

Put one end of the towel into each jar and let the middle hang over the lid.

Let this experiment sit untouched for several days. The solution will move along the towel and drip down the middle of the towel onto the jar lid. Crystal stalagmites will start growing up from the lid and stalactities will grow down from the towel. If you wait long enough, they will meet in the middle. 27

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ou can even grow crystal gardens. Many types of crystal gardens can be grown by pouring a simple solution over different objects in a pan. Your grown-up lab assistant can help you make this solution. Just be careful to keep your laboratory clean and to clean up any spills, quickly. Keep the window cleaner away from your face! The following ingredients will make enough solution for many crystal gardens.

MM @t¥SM mm mUfVIQN WHAT YOU WILL NEED ♦ 4 tbsp. of strong ammoniabased blue window cleaner. ♦ measuring spoons ♦ 1 spoon

# 1 clear plastic cup # 2 tbsp. liquid laundry bluing (available in the laundry product section of your store) # 2 tbsp. salt

Pour 2 tablespoons of bluing, and 2 tablespoons of salt into the cup. Stir slowly.

Slowly add 4 tablespoons of window cleaner. Mix well.

Now you are ready to start a crystal garden. Don’t pour the solution over the objects you choose - spoon it so that only a small amount remains in the bottom of the pan. Plastic containers can be used too. 28

WHAT YOU WILL NEED ♦ newspaper ^ 1 bowl, pan, or margarine container. ♦ the basic crystal garden solution (pg. 28) ♦ 1 spoon

Fold a piece of newspaper and place it into a container.

Crumple another piece of newspaper and place it on top of the folded one.

Slowly spoon the solution on top of the newspaper. Wait a day or two. What happened? 29

WHAT YOU WILL NEED ♦ assorted small items such as marbles, pieces of wood, plastic beads, paper clips, etc. ♦ 1 bowl, pan, or margarine container. ♦ the basic crystal garden solution (pg. 28) ♦ 1 spoon ♦ 1 styrofoam cup

Put the items into the cup.

Slowly pour the solution over the items.

Place the cup into a container. Crystals will start forming within a few days. 30

WHAT YOU WILL NEED ♦ assorted rocks ♦ 1 bowl, pan, or margarine container. ♦ the basic crystal garden solution (pg. 28) ♦ 1 spoon

Arrange the rocks in the container.

Slowly spoon the solution onto the rocks, leaving only a small amount in the bottom of the container.

Wait a day. How does your crystal garden look?

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a ou can keep track of your crystal experiments on the following chart. Fill in the date, the name of the experiment, and what happened each day. vV.-

DATE

EXPERIMENT Stalactites and

71/23/93

Stalagmite s

PROGRESS/RESULT Towel strip is saturated and starting to drip.

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$6.95

Crystals are all around us. We sprinkle salt crystals on our french fries and pour sugar crystals in our iced tea. Some crystals fall from the sky.*You know these as snowflakes. And some crystals are found deep within the earth. But what are crystals and how do they growl Grow Your Own Crystals will give you the answers to

these questions and more. You will find out about crystal shapes, how light affects crystals, and the importance of crystals in our everyday lives. Use the rocks included in this kit to grow your own crystals. Then get ready to grow your own crystal gardens from simple solutions and household items. Now you can explore the world of crystals. Just add a cup of curiosity and a few tablespoons of patience!

RECOMMENDED FOR AGES 6 AND UP ADULT SUPERVISION REQUIRED