GenreGenre Comprehension SkillComprehension Skill Text FeaturesText Features Science ContentScience Content Nonfi ctionNonfi ction Picture CluesPicture Clues • Captions• Captions Natural ResourcesNatural Resources • Labels• Labels • Glossary• Glossary Scott Foresman Science 2.5Scott Foresman Science 2.5 ì<(sk$m)=bdhidb<ì<(sk$m)=bdhidb<ISBNISBN 0-328-13783-90-328-13783-9 +^-Ä-U-Ä-U+^-Ä-U-Ä-U
Vocabulary Extended Vocabulary What did you learn? boulder atoms erosion crystal 1. What is the difference between minerals facets transparent and opaque gems? natural resource opaque pollution precious 2. Name two gemstones that come recycle semiprecious from ancient plants. sand synthetic weathering transparent 3. In this book you read about diamonds. Write toby Joyce A. Churchill explain how diamonds are found and turned into gemstones. Use words from the book as you write. 4. Picture Clues Which mineral is harder, gypsum or quartz? Use the Mohs Hardness Scale on pages 8 Picture CreditsEvery effort has been made to secure permission and provide appropriate credit for photographic material. and 9 to answer this question. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd). Scott Foresman/Dorling Kindersley would like to thank the Natural History Museum, London/DK Images for the use of photos on pages Opener, 4 (BC), 5 (C), 7 (TR, BC, BR), 8 (BL, BCL, BCR, BR), 9 (BL, BCL, BC, CRB, CR), 10 (TL), 12 (CR), 13 (CR), 14 (BR), 16 (BL), 17 (TL), 21 (TCL, TC, TR, CRA, CRB, BCR, BC, BCL, CLB, CL, CLA, TCL), 22 (TR), 23 (CR, B). Unless otherwise acknowledged, all photographs are the copyright © of Dorling Kindersley, a division of Pearson. ISBN: 0-328-13783-9 Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05
What You Already Know Rocks are all around us wherever we live. They are a natural resource of the Earth. Rocks can be large boulders. Sometimes they are broken into small pieces. They can even be fi nely ground up, like sand. garnet crystals on a white rock Over a long time water from rivers and lakes changes rocks. Ice and wind also slowly change rocks and soil. These changes are called erosion and weathering. Pollution happens when harmful things are put into the environment. We recycle materials to keep the Earth clean and protect its natural resources. Minerals are natural resources found in rocks. Some kinds of minerals are very special. Most gemstones are special minerals. In this book you will learn how we fi nd gemstones and why we value them. 2 3
Crystals and Gems Cutting Gems Minerals are made of atoms. An atom is the Diamonds and other gems are cut in special tiniest part of all things. Some atoms can come ways so that they refl ect together to make crystals. A crystal is a group light. The sides of a cut of atoms in a pattern, like eggs in an egg crate. gem are called facets. Crystals come in different sizes. Rock salt comes in large crystals you can see. uncut Many gems are also large crystals. Gems that diamond are crystals were formed underground long ago. Volcanoes and earthquakes push Pearls grow inside them to the surface. When gems oyster shells. cut reach the surface, people can diamond find them. pearls Not all gems come from the Earth. Pearls grow inside oyster shells. They are shiny and beautiful when they come from the oyster. Most gemstones have to be cut by experts. Gem cutters can make tiny rainbows of light Different crystal bounce off a gem. The crystal patterns in the gem patterns can grow next to each other. make the light do this. 4 5
Diamonds can be found under the ground. The diamonds in People mine diamonds in many countries in this pan are not the world. cut or polished. Sometimes miners fi nd diamond ore along rivers in sand and gravel. They use small pans and water to collect diamonds. It takes sharp eyes to tell which stones are the diamonds! Gems can be precious or Diamond stones have to be sorted, polished, semiprecious. Gems that are and cut before they can become gems. hard to fi nd or collect are called precious. Gems that are easier to fi nd are called semiprecious. a diamond mine Scientists can also make synthetic gems. in South Africa These are copies that look like real gems. Scientists grow crystals in a special container. Then they heat and apply pressure to the crystals. People buy synthetic gems because they cost less than real ones. Synthetic gems look just like real gems. synthetic synthetic ruby crystal cut ruby 6 7
How hard are Frederick Mohs was a scientist minerals? from Germany. In 1822 he found 10 a way to show how hard different diamond minerals are. He gave minerals Minerals can be hard or soft. Chalk is a soft different numbers depending on mineral. You can scratch chalk with your their hardness. This is called the fingernail and leave a mark. Soft minerals break Mohs scale. into pieces. Their atoms link lightly together. Look at the scale below. Diamonds are the hardest mineral. They have Soft minerals have low numbers. atoms made of carbon. The atoms in a diamond Talc is very soft. It is number 1 on link together like a tight web. A diamond is the scale. Hard minerals get high strong enough to cut through other rocks. numbers. Diamonds are number 10. People use diamonds in cutting tools. 9 corundum The Mohs scale shows how hard minerals are. 8 topaz 1 2 3 4 5 6 7 talc gypsum calcite fl uorite apatite feldspar quartz 8 9
This rock from a volcano Quartz has a diamond in it. Quartz can be found in small streams, in rivers, and on beaches. Quartz is made of crystals and is quite hard. diamond ring Many semiprecious gems are made Diamond from quartz. quartz Quartz can be transparent. beads This means you can see through it, Diamonds were formed deep in the Earth like water. Some quartz is opaque. many years ago. Diamonds need to be dug or This means you can’t see through blasted out of the ground. One of the most it at all, like milk. famous diamond mines is in South Africa. There are many kinds of quartz. Diamond ore is loaded into trucks and taken Amethyst quartz is purple. Citrine to a crusher. Crushed ore is then taken to be quartz comes in shades of washed. Diamonds are separated from the transparent orange. Rose waste material. The diamonds are sorted into quartz is pink. five thousand different kinds! They are sorted by size, shape, color, and value. Most diamonds are clear, like glass. Some can be light yellow. Light refl ects through the patterns of their crystals. That is why diamonds sparkle. Most diamonds have facets like Amethyst is a type of quartz. Can you see the a baseball diamond cut into them. patterns of the crystals? 10 11
Ruby Rubies come in all shades of red. They are precious gemstones. Kings and queens in Europe used rubies in their crowns. Rubies are cut from a mineral called corundum. It is very hard but not as hard as a diamond. Rubies come from mines in Asia and Can you see the star Africa. Some countries where they are found in this sapphire? are Myanmar, Sri Lanka, and Thailand. Sapphire Sapphires are precious gems. They can be pale blue or almost sapphire black. Sapphires are a hard, in rock cut ruby transparent stone. Just like rubies, they are made of corundum. Sapphires are found in Asia. They are mined in Thailand, India, Sri Lanka, and Myanmar. They are also found in Australia. The Edwardes Ruby In the United States sapphires have been is so large it is kept in a museum. found in the state of Montana. 12 13
Opal Emerald Opals are made up of tiny Emeralds are precious gems. spheres. A sphere is a shape They are made of a mineral like a ball. dark opal called beryl. It is a hard mineral One opal stone can be red, pendant with layers of crystals. green, blue, and yellow. The colors Emeralds have been valued for polished in an opal come from fl aws. A fl aw is a little thousands of years. The ancient emerald crack or break in the stone. It can also be a small Egyptians mined emeralds and piece of something trapped in the stone. These used them to make jewelry. The flaws make opals beautiful. They also make opals fi nest emeralds today are found softer than other gems. in the country of Colombia, in Opals are found in rocks. South America. They have been Many opals come from mined there for more than cut emerald Australia. Some come four hundred years. from Nevada, in the United States. The top of this crystal is a green emerald. How many colors can you see in this uncut opal? 14 15
Topaz Another gemstone made from tiny crystals is topaz. It comes in many pale colors. Topaz can be brown, blue, or green. Some topaz is red. It can also be colorless. Uncut moonstone refl ects silver, blue, Topaz is a hard mineral. It can be cut into and orange. many interesting shapes. Topaz is a semiprecious Moonstone gem. It is often used for rings and other jewelry. Topaz is found in Russia, Brazil, and When light refl ects off moonstone, it glows Australia. It is also like light from the Moon. Moonstone is made mined in Mexico and from a mineral called feldspar. Half of all the the United States. rocks on Earth are made of feldspar. Moonstones are found in several countries. Many are mined in Sri Lanka and Tanzania. They are also found in the United States. topaz ring This topaz has many moonstone fl aws at the bottom. necklace 16 17
Tree sap was a soft, Jet sticky trap for this insect. The sap Jet is also different from many other gems. turned into hard amber. It is sometimes called black amber. Jet is not made from crystals. It comes from ancient Amber plant parts. Some jet used to be wood! Millions of years of pressure under the Earth changed the wood into a black mineral. Like amber, Amber is different from many other gems. jet can be easily polished. It is not made of crystals. Amber is made of resin, Jet is mined in Spain, or sap, from ancient trees. Soft tree resin takes France, and Germany. millions of years to turn into hard amber. Most It is also found in Russia amber is yellow or brown. Amber can also be red, and the United States. green, or blue. Shiny, black stones in jet earrings A piece of amber is very light. It is often jewelry are often pieces transparent. You can sometimes see insects, of jet. leaves, or moss trapped inside. Scientists study animals and plants trapped in amber to learn about life long ago. Look for the wood grain in amber beads this piece of jet. 18 19
Special Gems January Gemstones have been special for thousands garnet of years. Long ago, kings and queens wore December February precious gems in their crowns. Pirates sometimes turquoise amethyst raided ships to steal the jewels. Many early peoples buried their rulers along with precious November March gems. Today, you can see the jewels from their topaz aquamarine tombs in many museums. People in the past thought gems could help them. Emeralds were worn to protect people Which of these from animal bites. Topaz was thought to bring birthstones matches friends. Rubies were worn to protect people from your birthday month? feeling sad. October April Many people still like to give gemstones as opal diamond gifts for special celebrations. In many countries in the world, people give each other a ring with September May sapphire emerald a gemstone when they get married. People also give gemstones as birthday gifts. Did you know there is a special list of gemstones for each month of the year? These are called birthstones. August June peridot pearl July ruby 20 21
Our Hidden Proustite is a crystal mineral that is purple Treasure like amethyst. Rocks are made up of minerals. Minerals are found all over the Earth. Gemstones are a special Gemstones that are rare are called group of minerals. Many precious stones. Those that are more easily come from deep in the found are called semiprecious stones. Earth. Some have been People have valued gemstones for pushed up to the surface thousands of years. They are of the Earth by volcanoes. some of our most beautiful Gemstones are taken natural resources. out of rocks through mining. They are washed and polished. Facets are cut into them so that they can refl ect light from their crystal patterns. amber sapphire amethyst 22 23
Vocabulary Extended Vocabulary What did you learn? Glossary boulder atoms erosion crystal 1. What is the difference between minerals facets transparent and opaque gems? atoms the smallest parts of all things natural resource opaque pollution precious 2. Name two gemstones that come crystal a group of atoms in a pattern from ancient plants. recycle semiprecious facetssand sides cut into a gemstonesynthetic weathering transparent 3. In this book you read about diamonds. Write to opaque something you cannot see explain how diamonds are found through, like milk and turned into gemstones. Use words from the book as you write. precious the most rare and valuable gemstones 4. Picture Clues Which mineral is harder, gypsum or quartz? Use the semiprecious the less rare and less valuable Mohs Hardness Scale on pages 8 Picture Credits gemstones and 9 to answer this question. Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).synthetic something made by people Scott Foresman/Dorling Kindersley would like to thank the Natural History Museum, London/DK Images for the use of photos on pages Opener, 4 (BC), 5 (C), 7 (TR, BC, BR), 8 (BL, BCL, BCR, BR), 9 (BL, BCL, BC, CRB, CR), 10 (TL), 12 (CR),13 (CR), 14 (BR), 16 (BL), 17 (TL), 21 (TCL, TC, TR, CRA, CRB, BCR, BC, BCL, CLB, CL, CLA, TCL), 22 (TR), 23 (CR, B).and machines Unless otherwise acknowledged, all photographs are the copyright © of Dorling Kindersley, a division of Pearson. transparent clear, see-through ISBN: 0-328-13783-9 Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 0524
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