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Rocks and Minerals

Rocks and Minerals

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Rocks and Minerals

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  1. Rocks and Minerals • Minerals (by def) - naturally occurring - inorganic - solid - definite chemical composition - a crystal structure

  2. Rocks and Minerals 1. Naturally Occurring mineral: quartz pyrite Not mineral: cement, steel

  3. Rocks and Minerals 2. Inorganic - does not come from anything living Ex: coal, pearls Amber (not minerals)

  4. Definite Chemical Composition

  5. Rocks and Minerals 4. Solids: Have definite size/volume and a definite shape Ex: oil, lava, magma

  6. Rocks and Minerals 5 Crystal Shape: Atoms arranged in repeating patterns.

  7. Mineral Formation 1. From Cooling lava/Magma 2. When water evaporates, dissolved minerals remain behind (precipitate out)

  8. Identifying Minerals Identified by Physical and Chemical properties Physical: Color, Streak, Luster, Hardness, Density Chemical: reactivity, special properties

  9. Physical Properties 1. Color: (vary due to impurities) a. Some minerals have only one color - olivine: green - sulfur: yellow b. Others have many colors - quartz: clear, pink, purple, white, smoky - hematite: black, grey red-brown, dark red

  10. Physical Properties 2. Streak: color of powder when mineral is rubbed on a streak plate - Streak never changes Ex: Hematite: color varies Dark red, reddish brown, grey Streak: always reddish brown

  11. Physical Properties 3. Luster: the way a mineral shines or reflects light from its surface 2 types Metallic: shines/reflects light like a metal (quarter) Nonmetallic: pearly, glassy, dull, waxy, brilliant

  12. Mineral Hardness 4. A measure of how easily a mineral can be scratched 1 softest mineral 10 hardest mineral A mineral with a hardness 4 can scratch itself and anything below

  13. Mineral Hardness/Common Objects 2.5 Fingernail 3.5 Copper Penny 4.5 Iron Nail 5.5 Glass Plate 6.5 Steel File 7 Streak Plate

  14. Mineral Properties 5. Cleavage and Fracture a. Cleavage: when a mineral splits along smooth flat surfaces. • Ex: Mica: one direction

  15. Mineral Properties Ex: Galena: three directions Determined by internal structure of mineral bonds between the atoms

  16. Mineral Properties: Cleavage Cleavage does not = Crystal Shape Crystal way mineral grows Cleavage way mineral breaks

  17. Mineral Properties Fracture: mineral breaks unevenly curved or irregular pieces rough/jagged surfaces

  18. Density or Heft 6. Density: How closely the atoms are packed into a given space. Different minerals of the same size have different densities and feel heavier or lighter

  19. Chemical Properties Calcite: reacts with HCL. It forms bubbles of carbon dioxide gas CaCO3 + 2HCl -> CaCl2 + H2O + CO2

  20. Special Properties Lodestone, a form of the mineral magnetite is naturally magnetic Calcite, shows double refraction Pitchblende: is radioactive

  21. Uses of Minerals A. Ore: A mineral that contains Metals and nonmetals that can be removed in usable amounts for a profit. 1. Metals: elements shiny surfaces conduct heat and electricity

  22. Metals 1. Iron: hematite: Fe2O3 Magnetite: Fe3O4 2. Aluminum: bauxite: Al(OH)3 3. Copper: Chalcopyrite: CuFeS2 malachite:Cu2CO3(OH)2

  23. Metals 4. Silver: Argenite: AgS2 5. Gold: Gold: Au 6. Mercury: cinnabar : HgS

  24. Alloy A mixture of two or more metals or a mixture of metals and nonmetals • Tin + Copper -> bronze • Zinc + Copper -> brass • Iron + chromium + limestone -> steel • Tin + lead -> pewter

  25. Nonmetals Elements dull surfaces, poor conductors of heat, electricity • Halite: Salt: NaCL • Gypsum: drywall • Sulfur: matches • Talc: talcum powder • Graphite: pencils

  26. Gems Minerals with desirable qualities hardness, color, luster, rare, durable Precious stones: diamonds, rubies sapphires Semiprecious: amethyst, garnet topaz Gems not minerals: pearls