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Minerals

Minerals. What is a Mineral?. Naturally Occurring. Inorganic. Solid. Definite Chemical Formula. Definite Crystal Structure. Naturally Occurring. Formed by natural processes not in the laboratory. Is an ice cube a mineral?. Is the ice on the windshield of a car a mineral?.

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Minerals

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  1. Minerals

  2. What is a Mineral? • Naturally Occurring • Inorganic • Solid • Definite Chemical Formula • Definite Crystal Structure

  3. Naturally Occurring • Formed by natural processes not in the laboratory. • Is an ice cube a mineral? • Is the ice on the windshield of a car a mineral? • Minerals manufactured by humans are not considered minerals.

  4. Inorganic • Formed by inorganic processes; not living • Minerals are not made from living things. • Coal is made of carbon. Is it a mineral?

  5. Solid • Minerals cannot be a gas or a liquid. - H2O as ice in a glacier is a mineral, but water is not.

  6. Definite Crystal Structure • Highly ordered atomic arrangement of atoms in regular geometric patterns • Minerals are crystals with a repeated inner structure. Apatite Feldspar Diamond Quartz

  7. Definite Chemical Formula • Gold (Au) • Calcite (CaCO3) • Minerals are expressed by a specific chemical formula. • Quartz (SiO2) • Pyrite (FeS2) • Minerals made of only one type of atom (element) are called native elements. • Gold • Copper • Silver

  8. Types of minerals • Minerals are most commonly classified by chemical composition. • The 2 main groups are silicates and nonsilicates.

  9. Silicates • Minerals containing a combination of silicon (Si) and oxygen (O) (most common elements in the earth’s crust) • Silicate minerals comprise about 90% of the Earth’s crust. • Silicates minerals often contain other elements such as aluminum, iron, magnesium, and potassium. • Granite is a rock comprised of the minerals feldspar, biotite mica and quartz.

  10. Feldspar • Feldspar minerals make up half of the Earth’s crust and is the main component of most of the rocks found on the Earth’s surface. • Feldspar contains Si, O, Al, K, Na, and Ca Feldspar

  11. Biotite Mica • Soft and shiny minerals that separate easily into sheets • Biotite is one variety of mica

  12. Quartz • Silicon dioxide ( SiO2) is the basic building block of many rocks

  13. Nonsilicates • Minerals that do not contain the combination of Si and O • Some of these minerals are made up of C, O, F, and S

  14. Classes of Nonsilicates • Native Elements • Carbonates • Halides • Oxides • Sulfates • Sulfides

  15. Native Elements • Native elements are composed of only 1 element • About 20 exist including Au, Pt, C, Cu, S and Ag

  16. Carbonates • Contain the combinations of carbon and Oxygen in their chemical structure • Calcite (CaCO3 ) is an example • Carbonates are used in cement, building stones and fireworks

  17. Halides • Form when atoms containing fluorine, chlorine, iodine, or bromine (halogens) combine with potassium or calcium • Halite (NaCl) is better known as rock salt • Fluorite can have many different colors Fluorite • Halides are often used in making fertilizers

  18. Oxides • Compounds formed when elements like aluminum or iron bond with oxygen • Corundum (Al2O3) and Magnetite (Fe3O4) are important oxides • Are used in abrasives and airplane parts

  19. Sulfates • Minerals containing sulfur and oxygen (SO4) • Gypsum (CaSO4 * 2H2O) is a common example • makes the white sand at White Sands National Monument in NM Gypsum • Sulfates are commonly used in cosmetics, toothpaste and paints

  20. Sulfides • Minerals containing one or more elements such as lead, iron, or nickel combines with sulfur • Galena (PbS) is a sulfide • Sulfides are used to make batteries, medicines and electronic parts Galena

  21. Composition of the Earth’s Crust • Eight Elements that make up over 98% of Earth’s Crust - Oxygen (O) - Silicon (Si) - Aluminum (Al) - Iron (Fe) - Calcium (Ca) - Sodium (Na) - Potassium (K) - Magnesium (Mg)

  22. Where Do Minerals Come From? In general, minerals form in two ways: Cooling magma - Crystallization of melted materials From solution - Crystallization of materials dissolved in water Magma a. At the surface b. Beneath the surface Evaporation

  23. Magma • Magma is molten material from the mantle that hardens to form rock. • Lava is magma that reaches the surface. • Minerals form as hot magma cools inside the crust, or as lava hardens on the surface. • When these liquids cool to the solid state, they form crystals.

  24. Size of Crystals • The rate at which the magma cools • Depends of several factors: • The chemical composition of the magma • The amount of gas the magma contains • When magma remains deep below the surface, it cools slowly over many thousands of years. • Slow cooling leads to the formation of large crystals. • Magma closer to the surface cools much faster, producing smaller crystals.

  25. Minerals from Hot Water Solutions • Sometimes, the elements that form a mineral dissolve in hot water and form a solution. • A solution is a mixture in which one substance dissolves in another. • When a hot water solution begins to cool, the elements and compounds leave the solution and crystallize as minerals. • This can happen on the ocean floor when ocean water seeps down through cracks in the crust.

  26. Minerals formed by Evaporation • Minerals can also form when solutions evaporate. Example: salt from sea water • Several other useful minerals also from by the evaporation of seawater: • Gypsum • Calcite crystals • Minerals containing potassium

  27. Minerals formed by Metamorphism • When rocks are put under extreme heat and pressure, the chemical composition of the rock can change, forming new minerals. • Examples: calcite, garnet, graphite, hematite, magnetite, mica and talc.

  28. How Are Minerals Identified? • Luster • Color • Hardness • Streak • Density • Crystal Shape • Cleavage and Fracture • Special Properties

  29. QUARTZ ROSE QUARTZ SMOKY QUARTZ Color • Not a reliable way to identify a mineral • Usually the first and most easily observed - Some minerals are the same color as others - Some minerals can have many colors

  30. Luster • General appearance of a mineral surface in reflected light Glassy-Obsidian

  31. Examples of luster • Vitreous: similar to glass • Metallic • Resinous: resembles the way plastic reflects light • Pearly: resembles the way pearls shine • Greasy: resembles the way petroleum jelly or a greasy surface reflects light • Silky: resembles the way silk reflects light • Earthy: dull, may be rough or dusty • Waxy • Adamantine: resembles the way a diamond shines • Fibrous – looks like fibers • Pitchy – looks like tar

  32. Hardness • Resistance to scratching by different items; “scratchability” • Mohs Hardness Scale is used to determine the hardness of minerals by comparing them to substances of known hardness.

  33. 9 10 Mohs Mineral Hardness Scale Softest 1) Talc 2) Gypsum 3) Calcite 4) Fluorite 5) Apatite 6) Feldspar 7) Quartz 8) Topaz 9) Corundum 10) Diamond 1 5 2 6 3 7 Hardest 4 8

  34. Streak • The color of a finely powdered mineral • Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate)

  35. Density • The amount of matter in a given space • Specific Gravity is the comparison of a substance’s density to the density of water

  36. Crystal Shape • Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming

  37. QUARTZ BIOTITE Cleavage and Fracture • Cleavage is the tendency of a mineral to split or crack along parallel or flat planes. • Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes. Obsidian 1 Direction of Cleavage No Cleavage Conchoidal Fracture

  38. Fracture

  39. Special Properties • Glowing under ultraviolet light (Fluorite) • Magnetism (Magnetite) • Taste (Halite) • Smell (Sulfur) • Reaction to HCl (Calcite) • Double refractive - a thin, clear piece of calcite placed over an image will cause a double image • Radioactivity - minerals containing radium or uranium can be detected by a Geiger counter

  40. Economic Importance of Minerals • Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold

  41. Every American Requires 40,000 Pounds of New Minerals per Year At this level of consumption the average newborn infant will need a lifetime supply of: - 795 lbs of lead (car batteries, electric components) - 757 lbs of zinc (to make brass, rubber, paints) - 1500 lbs of copper (electrical motors, wirings - 3593 lbs aluminum (soda cans, aircraft) - 32,700 lbs of iron (kitchen utensils, automobiles, buildings) - 28,213 lbs of salt (cooking, detergents) - 1,238,101 lbs of stone, sand, gravel, cement (roads, homes)

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