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Mineral Characteristics

Mineral Characteristics. A mineral is a naturally occurring, inorganic solid with a specific chemical composition and a definite crystalline structure. Naturally occurring means they are formed by natural processes.

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Mineral Characteristics

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  1. Mineral Characteristics • A mineral is a naturally occurring, inorganic solid with a specific chemical composition and a definite crystalline structure. • Naturally occurring means 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. A crystal 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. Definite Crystalline Structure

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

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

  5. Mineral Groups

  6. 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. 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. Oxides • Oxides are compounds of oxygen and a metal. • Hematite (Fe2O3) and magnetite (Fe3O4) are common iron oxides and good sources of iron.

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

  12. 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

  13. 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

  14. Mineral Identification • Geologists rely on several simple tests to identify minerals. • These tests are based upon a mineral’s physical and chemical properties.

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

  16. Color - Color is easy to see but not always reliable because: • Many minerals have same color • Color can change.

  17. 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).

  18. 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.

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

  20. 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.

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

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

  23. 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.

  24. 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.

  25. 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.

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

  27. 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.

  28. 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.

  29. 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.

  30. 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.

  31. 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.

  32. Identifying Minerals Section Assessment 1. Match the following terms with their definitions. ___ streak ___ hardness ___ cleavage ___ fracture 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

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