1 What Is a Mineral? Critical Thinking

Home , Carbonate mineral, Oxide mineral, Silicate mineral

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CHAPTER 3 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 STUDY TIP forms crystals and is always made of the same elements. Learn New Words As you The figure below shows four questions that you can ask read, underline words you in order to learn whether something is a mineral. don’t understand. When you fi gure out what they mean, write the words and their Is it nonliving? defi nitions in your notebook. Minerals are inorganic. Does it have a This means that they are crystalline structure? not made of living things Minerals are crystals. or their remains. Each mineral has a certain crystal structure that is always the same. Is it a solid? Minerals are not Does it form TAKE A LOOK gases or liquids. naturally? Minerals are not 1. Explain Why are made by people. diamonds that are made by people not considered minerals? All minerals have four features, as described in the fi gure.

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.

SECTION 1 What Is a Mineral? continued

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 READING CHECK only one element is called a native element. Each element is made of only one kind of atom. An 3. Deﬁ ne What is a compound? atom is the smallest part of an element that has the prop- erties of that element. Like other compounds, minerals are made up of atoms of one or more elements.

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 READING CHECK repeating a pattern of atoms. 4. Explain What causes The shape of a crystal depends on how the atoms in it minerals to form crystals? 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.

Real crystals of gold may not be perfect cubes because the crystals may be damaged or not form TAKE A LOOK completely. However, the 5. Identify What shape are Crystals of gold form atoms are still arranged in gold crystals? cubes because of the way a cubic pattern. their atoms are arranged.

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 TAKE A LOOK 6. Identify What two elements are found in all of the minerals in the ﬁ gure? Explain your answer. Quartz is a mineral Mica breaks into Feldspar is also common in the that is found in many sheets easily. rocks of the Earth’s crust. Feldspar rocks of the Earth’s can contain many elements other crust. 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 Oxides are minerals that contain compounds of oxygen and Native elements are another element, such minerals that are as iron or aluminum. made of only one Rubies and sapphires Corundum element. Copper, gold, are forms of the min- silver, and diamonds eral corundum, which are native elements. Copper is an oxide mineral.

Carbonates are Sulfates are minerals minerals that contain that contain compounds TAKE A LOOK compounds of carbon of oxygen and sulfur. 7. Compare How are and oxygen. Calcite is a Gypsum is a sulfate sulfate minerals different carbonate mineral. Calcite mineral. Gypsum from sulfi de minerals? Halides are miner- Sulfi des are minerals that als that contain the contain compounds of elements fl uorine, sulfur and an element chlorine, iodine, or other than oxygen, such as bromine. Fluorite lead, iron, or nickel. Galena Fluorite and halite are halide and pyrite (“fool’s gold”) Galena minerals. are sulfi de minerals.

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 mineral a naturally formed, inorganic solid that two or more different elements joined by has a deﬁ nite chemical structure chemical bonds nonsilicate mineral a mineral that does not crystal a solid whose atoms, ions, or molecules contain compounds of silicon and oxygen are arranged in a regular, repeating pattern silicate mineral a mineral that contains a element a substance that cannot be separated combination of silicon and oxygen and that or broken down into simpler substances by may also contain one or more metals chemical means

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.

4. at the poles 2. If two contour lines crossed, the point at 5. the prime meridian and the 180° meridian which they crossed would have to have two elevations. It is not possible for one point to have more than one elevation. SECTION 2 MAPPING THE EARTH’S SURFACE 3. the change in elevation between two contour lines 1. Moving information from a curved surface to a flat surface causes distortions. 4. 50 m 2. a way of transferring information from a 5. colors and symbols globe to a flat surface 6. gentle, steep, higher 3. Longitude lines are equally spaced. Latitude lines are unequally spaced. Review 1. lines on a map that connect points of equal 4. The cone touches the globe at each line of longitude. elevation 2. Maps of areas with high relief have large 5. north and south contour intervals. Maps of areas with little 6. The poles represent natural points at which relief have small contour intervals. a plane can touch the Earth’s surface. 3. 7. at the point of contact Feature Color on a topographic map 8. Road maps are often used to show dis- Contour lines brown tances. Equal-area projections show dis- Bodies of water blue tances accurately. Major roads red 9. shape Buildings and bridges black 10. in symbols Wooded areas green 11. Texas Cities gray or red 12. so that people can interpret the symbols on 4. elevation, bodies of water, major roads, the map bridges, railroad tracks 13. gathering information on a place without 5. about 145 m touching it 6. a closed circle 14. about 262 km 15. a system of satellites that orbit Earth Chapter 3 Minerals of the 16. Orbit Earth and send signals to the surface. Earth’s Crust 17. a system on a computer that shows information about an area SECTION 1 WHAT IS A MINERAL? 1. Minerals form naturally. Review 2. It is not a mineral, because it is not inorganic. Both show the features of the Earth’s sur- 1. a substance made of two or more elements face as they would appear if they were 3. bound together projected on a curved piece of paper. Cylindrical projections project the features 4. the regular pattern of atoms that make them up onto a cylinder. Conic projections project 5. cubes the features onto a cone. 6. All are silicate minerals, so all contain 2. title, scale, indicator of direction, legend, date silicon and oxygen. 3. equal-area projection 7. Sulfate minerals contain compounds of 4. conic projection sulfur and oxygen; sulfide minerals contain compounds of sulfur and another element. 5. Radar can penetrate thick clouds and collect images of the land beneath. Review satellites, GPS, GIS 6. 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 1. the height of a point above sea level are made up of only one kind of atom.

3. The crystal’s shape is determined by the 9. These appliances run on electricity. If arrangement of atoms or molecules in the electricity couldn’t move through them crystal. easily, they might not work correctly. 4. Water is not a solid. 10. calcite, quartz 5. Silicate minerals contain compounds of sili- 11. impurities con and oxygen. Nonsilicate minerals do not contain compounds of silicon and oxygen. Review 6. native elements, oxides, sulfides, sulfates, 1. An ore is a rock or mineral that has enough halides, carbonates useful material in it to be mined at a profit.

2. Type of Main features Common objects SECTION 2 IDENTIFYING MINERALS material made from it 1. It can react with air or water. Metal has shiny surfaces, wires, cars, does not transmit electronics 2. A mineral’s color may change, but its streak light, transmits is always the same. heat and electricity easily, can be rolled 3. conchoidal into sheets or 4. 19 times stretched into wires the resistance of a mineral to being Nonmetal has shiny or dull cement, 5. surfaces, does not computer chips, scratched transmit heat or glass No, because orthoclase is harder than apatite. electricity easily, 6. transmits light 7. They glow. 3. evaporation, metamorphism, deposition Review 4. Open-pit mines: gold 1. Minerals with cleavage break along smooth, Quarries: gravel flat surfaces. Minerals with fracture break Strip mines: coal along curved or irregular surfaces. 2. The same mineral can have many different colors. Chapter 4 Rocks: Mineral 3. hardness, streak, cleavage or fracture, luster, Mixtures density SECTION 1 THE ROCK CYCLE 4. The mineral’s hardness is probably about 4. 1. limestone, granite Calcite has a hardness of 3. Apatite has a 2. Weathering causes rock to break down into hardness of 5. Since apatite scratches the smaller pieces. mineral but calcite doesn’t, the mineral’s hardness must be somewhere between 3 and 5. 3. water, wind, ice, gravity 5. 2.6 4. Igneous rocks form when melted rock cools. Metamorphic rocks form when rock is heated (but does not melt) and its SECTION 3 THE FORMATION, MINING, composition changes. AND USE OF MINERALS 5. One possible path: Sedimentary rocks melt 1. Metamorphism: garnet, graphite, talc and cool to form igneous rocks. Reaction: gold, copper, pyrite 6. by studying its features gold, copper 2. 7. 45% iron, coal, salt 3. 8. the sizes of the sediment particles it is 4. horizontal, vertical, angled formed from 5. pollution and habitat destruction 9. when melted rock cools slowly underground 6. When mineral materials are recycled, less of the minerals have to be mined from the Review Earth. 1. Weathering is the process by which water, 7. Silver: electronics, jewelry wind, ice, and heat break down rock. Erosion is the process by which sediment is Bauxite: aluminum cans, utensils transported from its source. 8. ilmenite, magnetite, bauxite, beryl