Name Class Date. Does it have a crystalline structure? Minerals are crystals. Each mineral has a certain crystal structure that is always the same.

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1 CHAPTER 1 1 What Is a Mineral? SECTION Minerals of the Earth s Crust 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. Is it a solid? Minerals are not gases or liquids. Does it have a crystalline structure? Minerals are crystals. Each mineral has a certain crystal structure that is always the same. Does it form naturally? Minerals are not made by people. All minerals have four features, as described in the figure. 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. 1. Explain Why are diamonds that are made by people not considered minerals? 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. Critical Thinking 2. Apply Concepts Coal is made from the remains of dead plants. Is coal a mineral? Explain your answer. Interactive Textbook 1 Minerals of the Earth s Crust

2 SECTION 1 What Is a Mineral? continued READING CHECK 3. Define What is a compound? COMPOUNDS AND ATOMS 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. READING CHECK 4. Explain What causes minerals to form crystals? 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. 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. Interactive Textbook 2 Minerals of the Earth s Crust

3 SECTION 1 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 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. Copper Oxides are minerals that contain compounds of oxygen and another element, such as iron or aluminum. Rubies and sapphires are forms of the mineral corundum, which is an oxide mineral. Corundum 6. Identify What two elements are found in all of the minerals in the figure? Explain your answer. 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. Calcite Fluorite Sulfates are minerals that contain compounds of oxygen and sulfur. Gypsum is a sulfate 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. Gypsum Galena 7. Compare How are sulfate minerals different from sulfide minerals? Interactive Textbook 3 Minerals of the Earth s Crust

4 Section 1 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. Interactive Textbook 4 Minerals of the Earth s Crust

5 F Inside the Restless Earth Answer Key Chapter 1 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 bound together 4. the regular pattern of atoms that make them up 5. cubes 6. All are silicate minerals, so all contain silicon and oxygen. 7. Sulfate minerals contain compounds of sulfur and oxygen; sulfide minerals contain compounds of sulfur and another element. 1. solid, inorganic, crystalline, naturally formed 2. An atom is the smallest part of an element that has all the qualities of that element. Elements are made up of only one kind of atom. 3. The crystal s shape is determined by the 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 SECTION 2 IDENTIFYING MINERALS 1. It can react with air or water. 2. A mineral s color may change, but its streak is always the same. 3. conchoidal times 5. the resistance of a mineral to being scratched 6. No, because orthoclase is harder than apatite. 7. They glow. 1. Minerals with cleavage break along smooth, flat surfaces. Minerals with fracture break along curved or irregular surfaces. 2. The same mineral can have many different colors. 3. hardness, streak, cleavage or fracture, luster, density 4. 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 SECTION 3 THE FORMATION, MINING, AND USE OF MINERALS 1. Metamorphism: garnet, graphite, talc Reaction: gold, copper, pyrite 2. gold, copper 3. iron, coal, salt 4. horizontal, vertical, angled 5. pollution and habitat destruction 6. 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 9. These appliances run on electricity. If electricity couldn t move through them easily, they might not work correctly. 10. calcite, quartz 11. impurities 1. An ore is a rock or mineral that has enough useful material in it to be mined at a profit. 2. Type of material Metal Nonmetal Main features has shiny surfaces, does not transmit light, transmits heat and electricity easily, can be rolled into sheets or stretched into wires has shiny or dull surfaces, does not transmit heat or electricity easily, transmits light Common objects made from it wires, cars, electronics cement, computer chips, glass 3. evaporation, metamorphism, deposition 4. Open-pit mines: gold Quarries: gravel Strip mines: coal Interactive Textbook Answer Key 35 Inside the Restless Earth