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Name Class CHAPTER 3 Date Minerals of the Earth’s Crust SECTION 1 What Is a Mineral? BEFORE YOU READ After you read this section, you should be able to answer these questions: • What are minerals? • What determines the shape of a mineral? • What are two main groups of minerals? What Are Minerals? A mineral is a naturally formed, inorganic solid that forms crystals and is always made of the same elements. The figure below shows four questions that you can ask in order to learn whether something is a mineral. Is it nonliving? Minerals are inorganic. This means that they are not made of living things or their remains. STUDY TIP Learn New Words As you read, underline words you don’t understand. When you figure out what they mean, write the words and their definitions in your notebook. Does it have a crystalline structure? Minerals are crystals. Each mineral has a certain crystal structure that is always the same. Is it a solid? Minerals are not gases or liquids. Does it form naturally? Minerals are not made by people. All minerals have four features, as described in the figure. TAKE A LOOK 1. Explain Why are diamonds that are made by people not considered minerals? Critical Thinking 2. Apply Concepts Coal is made from the remains of dead plants. Is coal a mineral? Explain your answer. You might not be familiar with the term “crystalline structure.” To understand what crystalline structure is, you need to know a little about how elements form minerals. Elements are pure substances that cannot be broken down into simpler substances. Oxygen, chlorine, carbon, and iron are examples of elements. Elements can come together in certain ways to form new substances, such as minerals. All minerals are made of one or more elements. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 37 Minerals of the Earth’s Crust Name SECTION 1 Class Date What Is a Mineral? continued COMPOUNDS AND ATOMS READING CHECK 3. Define What is a compound? Most minerals are made of compounds of several different elements. A compound is a substance made of two or more elements that are chemically bonded. For example, the mineral halite is a compound of sodium, Na, and chlorine, Cl. A few minerals, such as gold and silver, are made of only one element. A mineral that is made of only one element is called a native element. Each element is made of only one kind of atom. An atom is the smallest part of an element that has the properties of that element. Like other compounds, minerals are made up of atoms of one or more elements. CRYSTALS READING CHECK 4. Explain What causes minerals to form crystals? Remember that minerals have a definite crystalline structure. This means that the atoms in the mineral line up in a regular pattern. The regular pattern of the atoms in a mineral causes the mineral to form crystals. Crystals are solid, geometric forms of minerals that are formed by repeating a pattern of atoms. The shape of a crystal depends on how the atoms in it are arranged. The atoms that make up each mineral are different. However, there are only a few ways that atoms can be arranged. Therefore, the crystals of different minerals can have similar shapes. Although different minerals may form similar shapes, each mineral forms only one shape of crystal. Therefore, geologists say that a mineral has a definite crystalline structure. This means that crystals of a certain mineral always form the same shape. The mineral gold is made of atoms of the element gold. The atoms are arranged in a cubic pattern. TAKE A LOOK 5. Identify What shape are gold crystals? Crystals of gold form cubes because of the way their atoms are arranged. Real crystals of gold may not be perfect cubes because the crystals may be damaged or not form completely. However, the atoms are still arranged in a cubic pattern. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 38 Minerals of the Earth’s Crust Name SECTION 1 Class Date What Is a Mineral? continued How Do Geologists Classify Minerals? Geologists classify minerals based on the elements or compounds in the minerals. Two main groups of minerals are silicate minerals and nonsilicate minerals. SILICATE MINERALS Silicon and oxygen are two of the most common elements in the Earth’s crust. Minerals that contain compounds of silicon and oxygen are called silicate minerals. Silicate minerals make up more than 90% of the Earth’s crust. Most silicate minerals also contain elements other than silicon and oxygen, such as aluminum, iron, or magnesium. Common Silicate Minerals TAKE A LOOK 6. Identify What two elements are found in all of the minerals in the figure? Explain your answer. Quartz is a mineral that is found in many rocks of the Earth’s crust. Mica breaks into sheets easily. Feldspar is also common in the rocks of the Earth’s crust. Feldspar can contain many elements other than silicon and oxygen, such as potassium or sodium. NONSILICATE MINERALS Minerals that do not contain compounds of silicon and oxygen are called nonsilicate minerals. Some of these minerals are made of elements such as carbon, oxygen, fluorine, and sulfur. Types of Nonsilicate Minerals Native elements are minerals that are made of only one element. Copper, gold, silver, and diamonds are native elements. Carbonates are minerals that contain compounds of carbon and oxygen. Calcite is a carbonate mineral. Halides are minerals that contain the elements fluorine, chlorine, iodine, or bromine. Fluorite and halite are halide minerals. Copper Calcite Fluorite Oxides are minerals that contain compounds of oxygen and another element, such as iron or aluminum. Rubies and sapphires Corundum are forms of the mineral corundum, which is an oxide mineral. Sulfates are minerals that contain compounds of oxygen and sulfur. Gypsum is a sulfate Gypsum mineral. Sulfides are minerals that contain compounds of sulfur and an element other than oxygen, such as lead, iron, or nickel. Galena and pyrite (“fool’s gold”) are sulfide minerals. TAKE A LOOK 7. Compare How are sulfate minerals different from sulfide minerals? Galena Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 39 Minerals of the Earth’s Crust Name Class Date Section 1 Review SECTION VOCABULARY compound a substance made up of atoms of two or more different elements joined by chemical bonds crystal a solid whose atoms, ions, or molecules are arranged in a regular, repeating pattern element a substance that cannot be separated or broken down into simpler substances by chemical means mineral a naturally formed, inorganic solid that has a definite chemical structure nonsilicate mineral a mineral that does not contain compounds of silicon and oxygen silicate mineral a mineral that contains a combination of silicon and oxygen and that may also contain one or more metals 1. Identify What are four features of a mineral? 2. Compare What is the difference between an atom and an element? 3. Infer What determines the shape of a crystal? 4. Apply Concepts Why is the ice in a glacier considered a mineral, but the water in a river is not considered a mineral? 5. Describe What are the features of the two major groups of minerals? 6. List Give four types of nonsilicate minerals. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook 40 Minerals of the Earth’s Crust Earth Science Answer Key continued 4. at the poles 5. the prime meridian and the 180° meridian 2. If two contour lines crossed, the point at SECTION 2 MAPPING THE EARTH’S SURFACE 3. 1. Moving information from a curved surface 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 4. 5. 6. to a flat surface causes distortions. a way of transferring information from a globe to a flat surface Longitude lines are equally spaced. Latitude lines are unequally spaced. The cone touches the globe at each line of longitude. north and south The poles represent natural points at which a plane can touch the Earth’s surface. at the point of contact Road maps are often used to show distances. Equal-area projections show distances accurately. shape in symbols Texas so that people can interpret the symbols on the map gathering information on a place without touching it about 262 km a system of satellites that orbit Earth Orbit Earth and send signals to the surface. a system on a computer that shows information about an area Review 1. lines on a map that connect points of equal elevation 2. Maps of areas with high relief have large contour intervals. Maps of areas with little relief have small contour intervals. 3. Feature Color on a topographic map 6. Contour lines brown Bodies of water blue Major roads red Buildings and bridges black Wooded areas green Cities gray or red 4. elevation, bodies of water, major roads, bridges, railroad tracks 5. about 145 m 6. a closed circle Chapter 3 Minerals of the Earth’s Crust SECTION 1 WHAT IS A MINERAL? 1. Minerals form naturally. 2. It is not a mineral, because it is not inorganic. 3. a substance made of two or more elements Review 1. Both show the features of the Earth’s sur- 2. 3. 4. 5. which they crossed would have to have two elevations. It is not possible for one point to have more than one elevation. the change in elevation between two contour lines 50 m colors and symbols gentle, steep, higher face as they would appear if they were projected on a curved piece of paper. Cylindrical projections project the features onto a cylinder. Conic projections project the features onto a cone. title, scale, indicator of direction, legend, date equal-area projection conic projection Radar can penetrate thick clouds and collect images of the land beneath. satellites, GPS, GIS 4. 5. 6. 7. bound together the regular pattern of atoms that make them up cubes All are silicate minerals, so all contain silicon and oxygen. Sulfate minerals contain compounds of sulfur and oxygen; sulfide minerals contain compounds of sulfur and another element. Review 1. solid, inorganic, crystalline, naturally formed 2. An atom is the smallest part of an element that SECTION 3 TOPOGRAPHIC MAPS has all the qualities of that element. Elements are made up of only one kind of atom. 1. the height of a point above sea level Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook Answer Key 35 Earth Science Earth Science Answer Key continued 9. These appliances run on electricity. If 3. The crystal’s shape is determined by the electricity couldn’t move through them easily, they might not work correctly. 10. calcite, quartz 11. impurities arrangement of atoms or molecules in the crystal. 4. Water is not a solid. 5. Silicate minerals contain compounds of silicon and oxygen. Nonsilicate minerals do not contain compounds of silicon and oxygen. 6. native elements, oxides, sulfides, sulfates, halides, carbonates Review 1. An ore is a rock or mineral that has enough useful material in it to be mined at a profit. 2. SECTION 2 IDENTIFYING MINERALS 1. It can react with air or water. 2. A mineral’s color may change, but its streak 3. 4. 5. 6. 7. is always the same. conchoidal 19 times the resistance of a mineral to being scratched No, because orthoclase is harder than apatite. They glow. 3. 4. 5. Main features Common objects made from it Metal has shiny surfaces, wires, cars, does not transmit electronics light, transmits heat and electricity easily, can be rolled into sheets or stretched into wires Nonmetal has shiny or dull surfaces, does not transmit heat or electricity easily, transmits light cement, computer chips, glass 3. evaporation, metamorphism, deposition 4. Open-pit mines: gold Review 1. Minerals with cleavage break along smooth, 2. Type of material Quarries: gravel Strip mines: coal flat surfaces. Minerals with fracture break along curved or irregular surfaces. The same mineral can have many different colors. hardness, streak, cleavage or fracture, luster, density The mineral’s hardness is probably about 4. Calcite has a hardness of 3. Apatite has a hardness of 5. Since apatite scratches the mineral but calcite doesn’t, the mineral’s hardness must be somewhere between 3 and 5. 2.6 Chapter 4 Rocks: Mineral Mixtures SECTION 1 THE ROCK CYCLE 1. limestone, granite 2. Weathering causes rock to break down into smaller pieces. 3. water, wind, ice, gravity 4. Igneous rocks form when melted rock SECTION 3 THE FORMATION, MINING, AND USE OF MINERALS 5. 1. Metamorphism: garnet, graphite, talc Reaction: gold, copper, pyrite gold, copper iron, coal, salt horizontal, vertical, angled pollution and habitat destruction When mineral materials are recycled, less of the minerals have to be mined from the Earth. 7. Silver: electronics, jewelry Bauxite: aluminum cans, utensils 8. ilmenite, magnetite, bauxite, beryl 6. 7. 8. 2. 3. 4. 5. 6. 9. cools. Metamorphic rocks form when rock is heated (but does not melt) and its composition changes. One possible path: Sedimentary rocks melt and cool to form igneous rocks. by studying its features 45% the sizes of the sediment particles it is formed from when melted rock cools slowly underground Review 1. Weathering is the process by which water, wind, ice, and heat break down rock. Erosion is the process by which sediment is transported from its source. Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Textbook Answer Key 36 Earth Science