Mineral Characteristics

1. What is a mineral? Mineral Characteristics • A mineral is a naturally occurring, inorganic solid with a specific chemical composition and a definite crystalline structure. Naturally Occurring and Inorganic • That minerals are naturally occurring means that they are formed by natural processes. • All minerals are inorganic, meaning that they aren’t alive and never were alive during any part of their existence.

2. What is a mineral? Mineral Characteristics Definite Crystalline Structure • A crystal is is a solid in which the atoms or molecules are arranged in a definite pattern that is repeated over and over again. There are 6 crystal shapes.

3. What is a mineral? What is a mineral? • Earth’s crust is composed of about 3000 minerals. • Only about 30 minerals are common in Earth’s crust.

4. What is a mineral? Minerals Formation Minerals form by four major processes: • Magma hardening • Changes in pressure • Changes in temperature • Formation of hydrothermal solutions

5. What is a mineral? Mineral Groups

6. What is a mineral? Mineral Groups Silicates • Silicates are minerals that contain silicon and oxygen, and usually one or more other elements. • Silicates make up approximately 96 percent of the minerals found in Earth’s crust. • The most common minerals, feldspar and quartz, are silicates. • Ex: Olivine is Mg2SiO4

7. What is a mineral? Mineral Groups Carbonates • Carbonates are minerals composed of one or more metallic elements with the carbonate compound CO3. • Carbonates are the primary minerals found in rocks such as limestone, coquina, and marble. • Ex: Calcite is CaCO3

8. What is a mineral? Mineral Groups Oxides • Oxides are compounds of oxygen and a metal. • Hematite (Fe2O3) and magnetite (Fe3O4) are common iron oxides and good sources of iron.

9. What is a mineral? Mineral Groups Sulfates and Sulfides • Sulfates such as anhydrite (CaSO4) are composed of elements with the sulfate compound SO4. • Sulfides such as pyrite (FeS2) are compounds of sulfur and one or more elements.

10. Halides • Halides such as halite (NaCl) are made up of chloride or fluoride along with calcium, sodium, or potassium.

11. Mineral Groups Native elements • A native element such as silver (Ag) or copper (Cu) is made up of one element only.

12. What is a mineral? Mineral Groups

13. What is a mineral? Section Assessment 1. Match the following terms with their definitions. ___ mineral ___ crystal ___ magma ___ silicate B C D A A. minerals that contain silicon and oxygen, and usually one or more other elements B.a naturally occurring, inorganic solid with a specific chemical composition and definite crystalline structure C.a solid in which the atoms are arranged in repeating patterns D. molten material found beneath Earth’s surface

14. What is a mineral? Section Assessment 2. What are the two ways that minerals can form from a supersaturated solution? Mineral crystals can precipitate, or drop out of solution if the solution becomes supersaturated. Minerals can also form when liquid evaporates from a supersaturated solution leaving behind the elements which may begin to arrange into crystals.

15. What is a mineral? Section Assessment 3. Identify whether the following statements are true or false. _______ There are about 30 common minerals in Earth’s crust. _______ Slowly cooling magma produces small crystals. _______ Coal is a mineral. _______ Silicates are the most common minerals on Earth. _______ Well-defined crystal shapes are rare. true false false true true

16. End of Section 1

17. Identifying Minerals Mineral Identification • Geologists rely on several relatively simple tests to identify minerals. • These tests are based upon a mineral’s physical and chemical properties. • It is usually best to use a combination of tests rather than just one to identify minerals.

18. Mineral Properties • Minerals have certain physical properties that can be used to identify them. -color -luster -hardness -streak -density -crystal shape -breakage -special properties

19. Identifying Minerals Mineral Identification Color - Color is easy to see but not always reliable because: • Many minerals have same color • Color can change.

20. Identifying Minerals Mineral Identification Streak Streak is the color of powder scraped off a mineral when it is rubbed against a rough hard surface. You can find streak by rubbing a mineral across a piece of unglazed porcelain tile (a streak plate).

21. Identifying Minerals Mineral Identification Luster • Luster is the way that a mineral reflects light from its surface. • Metallic is shiny like a metal. • Nonmetallic luster might be described as dull, pearly, waxy, or silky.

22. Crystal Structure • A mineral may be identified by it’s crystal structure, one of the six previously mentioned.

23. Identifying Minerals Mineral Identification Hardness • Hardness is a measure of how easily a mineral can be scratched. • We use Moh's hardness scale. We use different tools to find the hardness- fingernail, penny, nail, glass plate and streak plate. Diamond, the hardest, is a10. Talc, the softest, is a 1. • Any mineral with a greater hardness than another mineral will scratch that softer mineral.

24. Identifying Minerals Mineral Identification Hardness

25. Identifying Minerals Mineral Identification Cleavage • Minerals break along planes where atomic bonding is weak. • Cleavageis the ability of a mineral to split relatively easily and evenly along one or more flat planes.

26. Fracture • Fracture is the ability of minerals to break with rough, or jagged edges.

27. Identifying Minerals Mineral Identification Density and Specific Gravity • Differences in weight are the result of differences in density, which is defined as mass per unit of volume. • Density is expressed as a ratio of the mass of a substance divided by its volume, or D = M/V. • Density reflects the atomic weight and structure of a mineral. • The most common measure of density used by geologists is specific gravity. • Specific gravity is the ratio of the weight of a substance to the weight of an equal volume of water at 4°C.

28. Identifying Minerals Special Properties • Special properties of minerals also can be used for identification purposes. • A type of calcite called Iceland spar causes light to be bent in two directions, a process known as double refraction, when it passes through the mineral. • Magnetite, an iron ore, is naturally magnetic.

29. Special Properties • Calcite (CaCO3) fizzes when it comes into contact with hydrochloric acid (HCl).

30. Identifying Minerals Mineral Uses • Minerals are virtually everywhere. • They are used to make computers, cars, televisions, desks, roads, buildings, jewelry, beds, paints, sports equipment, and medicines, just to name a few uses.

31. Identifying Minerals Mineral Uses Ores • An ore is a mineral that contains a useful substance that can be mined at a profit. • Examples of ores include Hematite, which contains the element iron and bauxite, which contains the element aluminum.

32. Identifying Minerals Mineral Uses Mines • Ores are removed by underground mining or from large, open-pit mines. • When a mine is excavated, unwanted rock and dirt, known as waste material, are dug up along with ore. • If the cost of separating the waste material becomes higher than the value of the ore itself, then the mineral will no longer be classified as an ore because it would no longer be economical to mine it. • The classification of a mineral as an ore may also change if the supply of or demand for that mineral changes.

33. Identifying Minerals Gems • Gems are valuable minerals that are prized for their rarity and beauty. • Gems such as rubies, emeralds, and diamonds are cut, polished, and used for jewelry. • In some cases, the presence of trace elements can make one variety of a mineral more colorful and thus more prized than other varieties of the same mineral.

34. Identifying Minerals Section Assessment 1. Match the following terms with their definitions. ___ streak ___ hardness ___ cleavage ___ fracture C D B A A. the ability to break with arc-like, rough, or jagged edges B.the ability to split relatively easily along one or more flat planes C.the color of a mineral when it is broken up and powdered D. a measure of how easily a mineral can be scratched

35. Identifying Minerals Section Assessment 2. How would an oversupply of ore possibly change the mineral’s classification as an ore? If an ore is over supplied, it could drive down prices for the ore. This may create a situation in which it would no longer be economical to mine material, thus the material would no longer be classified as an ore.

36. Identifying Minerals Section Assessment 3. What is specific gravity? Specific gravity is the ratio of the weight of a substance to the weight of an equal volume of water at 4ºC. It is a common measure of density used by geologists.

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38. Chapter Resources Menu Chapter Resources Menu Study Guide Section 4.1 Section 4.2 Chapter Assessment Image Bank

39. Section 4.1 Study Guide Section 4.1 Main Ideas • A mineral is a naturally occurring, inorganic solid with a specific chemical composition and a definite crystalline structure. There are at least 3000 known minerals in Earth’s crust. • A crystal is a solid in which the atoms are arranged in repeating patterns. The six main crystal systems are cubic, tetragonal, hexagonal, orthorhombic, monoclinic, and triclinic. • Minerals form from magma or from supersaturated solution. Most minerals are formed from the eight most common elements in Earth’s crust.

40. Section 4.1 Study Guide Section 4.1 Main Ideas • Oxygen readily combines with other elements to form a diverse group of minerals, including silicates, carbonates, and oxides. A silica tetrahedron is a three-dimensional shape structured like a pyramid. In a silica tetrahedron one silicon atom attaches to four oxygen atoms. • Other major mineral groups include sulfides, sulfates, halides, and native elements. Native elements such as silver or copper are made of one element only.

41. Section 4.2 Study Guide Section 4.2 Main Ideas • Minerals can be identified based on their physical and chemical properties. The most reliable way to identify a mineral is by using a combination of several tests. • A mineral’s color is generally the result of trace elements within the mineral. Texture describes how a mineral feels, and luster describes how a mineral reflects light. Cleavage and fracture describe how minerals break. • A mineral’s streak, hardness, and density are reliable methods of identification. Special properties of minerals such as magnetism also can be used for identification purposes.

42. Section 4.2 Study Guide Section 4.2 Main Ideas • An ore contains a useful substance that can be mined at a profit. If the cost of mining the ore becomes higher than the value of the ore, then the mineral is no longer classified as an ore. The classification of a mineral as an ore may also change if the supply of or demand for the mineral changes. • Gems are valuable minerals that are prized for their rarity and beauty. Trace elements can make one variety of a mineral more valuable than other varieties of the same mineral.

43. Chapter Assessment Multiple Choice 1. What special property can be used to help identify the mineral sphalerite? a. It fizzles when it comes in contact with HCl. b. It exhibits double refraction. c. A rotten-egg odor is produced during a streak test. d. It is naturally magnetic. Calcite reacts with HCl. Iceland sparandzircon exhibit double refraction when light is passed through them. Magnetiteis naturally magnetic.

44. Chapter Assessment Multiple Choice 2. A mineral with a metallic luster could be described as ___. a. silky c. pearly b. shiny d. waxy Silky, pearly, and waxy can all be used to describe nonmetallic luster.

45. Chapter Assessment Multiple Choice 3. Which ore is a source of iron? a. bauxite c. zircon b. rutile d. hematite Bauxite is an aluminum ore. The ore rutile is a source of titanium. Zircon contains no iron.

46. Chapter Assessment Multiple Choice 4. A silica tetrahedron contains ___ oxygen atoms. a. one c. three b. two d. four A silica tetrahedron is made up of one silicon atom bonded to four oxygen atoms.

47. Chapter Assessment Multiple Choice 5. Which of the following is an example of native element mineral? a. halite c. copper b. pyrite d. anhydrite A native element mineral is made up of only one element. Halite (NaCl), pyrite (FeS2), and anhydrite (CaSO4) all contain more than one element.

48. Chapter Assessment Short Answer 6. Why are crystals that form in well-defined shaped fairly rare? Most crystals form in restricted space.

49. Chapter Assessment Short Answer 7. What are the characteristics of minerals? To be a mineral, a material must be a naturally occurring, inorganic solid with a specific chemical composition, and a definite crystalline structure.

50. Chapter Assessment True or False 8. Identify whether the following statements are true or false. ______ About 90 known elements occur naturally in Earth’s crust. ______ Oxides are compounds of oxygen and another gas. ______ Pyrite has a hexagonal crystal system. ______ Ores must be mined at a profit. ______ Rubies are more valuable than diamonds. true false false true true