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  1. 1. Rocks & Minerals NOTES
  2. 2. What is a mineral? It is a substance which has a naturally occurring inorganic definite chemical composition ESRT Mineral Chart Click Here
  3. 3. Naturally Occurring Formed in nature & not made by people Inorganic Has not been made by or composed of life forms
  4. 4. <ul><ul><ul><li>Fossil Fuels are NOT a minerals because they comes from microogranisms </li></ul></ul></ul><ul><ul><ul><li>A pearl is NOT a mineral because it comes from an oyster </li></ul></ul></ul>
  5. 5. <ul><ul><li>Definite Chemical Composition </li></ul></ul><ul><ul><li>Solids composed of 1 or more chemical elements </li></ul></ul><ul><ul><li>All minerals are rocks </li></ul></ul><ul><ul><ul><li>Not all rocks are minerals </li></ul></ul></ul><ul><ul><ul><li>Rock is any naturally formed solid that is part of Earth or any other celestial body </li></ul></ul></ul><ul><ul><ul><li>Glasses are not minerals because their atoms are not arranged in a specific pattern </li></ul></ul></ul><ul><ul><li>- 20-30 common rock forming minerals </li></ul></ul>
  6. 6. Crystal Structure <ul><li>responsible for many of minerals chemical & physical properties such as crystal form, breaking pattern & hardness </li></ul><ul><li>Most rock-forming minerals are silicates </li></ul><ul><li>Silicate minerals have structure that results from various arrangements of tetrahedron-shaped unit on oxygen & silicon </li></ul><ul><ul><li>Tetrahedron can be arranged in different ways resulting in different breaking patterns </li></ul></ul>
  7. 7. Minerals have a definite chemical composition. What two elements, by mass, make up the greatest percentage of the Earth’s crust? silicon oxygen
  8. 8. Minerals have a definite chemical composition. These two elements combine to form compounds called silicates (SiO 4 )
  9. 9. Minerals have a definite chemical composition. They combine in a specific structure called a: silicon-oxygen tetrahedra
  10. 10. Mineral Formation: by 1 of 2 processes <ul><li>1. Inorganic Crystallization </li></ul><ul><li>- Process of organizing atoms to form crystalline solids </li></ul><ul><li>2. Recrystallizaiton </li></ul><ul><li>- From solids, liquids & gases associated with various rock-forming environments </li></ul>
  11. 11. Mineral Properties & Identification
  12. 12. <ul><li>- Crystal structure & chemical composition of minerals largely determine physical & chemical properties used to identify </li></ul>
  13. 13. What causes minerals to have different physical properties? their internal arrangement of atoms
  14. 14. The Main Physical Properties Used to Identify Minerals Color a poor indicator minerals can be multiple colors many minerals are the same color
  15. 15. The Main Physical Properties Used to Identify Minerals Streak the powder form of a mineral more reliable than color
  16. 16. Streak <ul><ul><li>Color of finely crushed residue or powder of a mineral </li></ul></ul><ul><ul><li>When you write on chalkboard, you observe streak of chalk </li></ul></ul><ul><ul><li>Streak of mineral usually consistent, making streak color more useful in identifying than mineral color </li></ul></ul>
  17. 17. Luster <ul><ul><li>Shine from an unweathered mineral’s surface </li></ul></ul><ul><ul><ul><li>Way a mineral looks in reflected light </li></ul></ul></ul><ul><ul><li>- 2 groups of luster </li></ul></ul><ul><ul><ul><li>Metallic </li></ul></ul></ul><ul><ul><ul><ul><li>shine like surface of clean stainless steel pot </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Example: Pyrite & galena </li></ul></ul></ul></ul><ul><ul><ul><li>Non-Metallic </li></ul></ul></ul><ul><ul><ul><ul><li>can be glassy like black hornblende & quartz </li></ul></ul></ul></ul><ul><ul><ul><ul><li>can be pearly like muscovite mica </li></ul></ul></ul></ul>
  18. 18. The Main Physical Properties Used to Identify Minerals Luster how light reflects off a mineral metallic non-metallic looks like a metal looks earthy, waxy, greasy or brilliant
  19. 19. Hardness The Main Physical Properties Used to Identify Minerals resistance to being scratched It is NOT the same as breaking! For example: You can break glass easily with steel. However, steel will not scratch glass.
  20. 20. Hardness The Main Physical Properties Used to Identify Minerals <ul><ul><li>Scratchability of minerals, not how easily it breaks </li></ul></ul>For example: Diamonds are hardest mineral, but if you drop an unmounted diamond on a tile floor it will break
  21. 21. MOH’S SCALE OF HARDNESS Diamond 10 (hardest) Apatit 5 Corundum 9 Flvorite 4 Topaz 8 Calcite 3 Quartz 7 Gypsum 2 Orthoclase 6 Talc 1 (softest) Mineral Hardness Mineral Hardness
  22. 22. <ul><ul><li>- Quick way to determine relative hardness is to use piece of window glass </li></ul></ul><ul><ul><li>1. If mineral scratches glass it is hard </li></ul></ul><ul><ul><li>2. If mineral doesn’t scratch glass it is soft </li></ul></ul>
  23. 23. Density <ul><ul><li>Each mineral has specific density or narrow range of densities </li></ul></ul><ul><ul><li>Often stated as specific gravity, which has not units </li></ul></ul><ul><ul><li>Specific gravity is density of mineral compared to density of water </li></ul></ul><ul><ul><li>Specific density good test to distinguish gemstones, because it doesn’t harm samples </li></ul></ul>
  24. 24. Cleavage <ul><ul><li>- Tendency of mineral to break along zones of weakness & form smooth to semi-smooth parallel sides or surfaces </li></ul></ul><ul><ul><li>- Cleavage surfaces can often be distinguished from sides without by having a shiner or more brilliant luster </li></ul></ul><ul><ul><li>- If minerals lack preferred zones of weakness, then it will demonstrate uneven breaking surface (fracture) </li></ul></ul>
  25. 25. Examples of Cleavage
  26. 26. Examples of Cleavage
  27. 27. Examples of Cleavage
  28. 28. Examples of Cleavage
  29. 29. Examples of Cleavage
  30. 30. Examples of Cleavage
  31. 31. Examples of Cleavage
  32. 32. Fracture The Main Physical Properties Used to Identify Minerals the mineral breaks randomly
  33. 33. One Mineral, Many Colors
  34. 34. Different Minerals Same Color
  35. 35. Crystal Structure <ul><ul><li>Outward geometric shape of mineral, crystal form, reflect structure </li></ul></ul><ul><ul><li>Orderly arrangement of atoms in mineral </li></ul></ul><ul><ul><li>Any mineral can have many different crystal shapes </li></ul></ul>
  36. 36. Other Mineral Properties <ul><ul><li>Some chemical properties of minerals are used for identification </li></ul></ul><ul><ul><ul><li>Reaction of a mineral with acid </li></ul></ul></ul><ul><ul><ul><li>When small amount of dilute HCl placed on mineral or rock containing calcite (CaCO3) will bubble (effervesce) – giving off CO2 </li></ul></ul></ul><ul><ul><ul><li>Dolomite distinguished from calcite, because dolomite will only bubble in acid after powdered </li></ul></ul></ul>
  37. 37. What two elements, by mass, make up the greatest percentage of the Earth’s crust? <ul><li>Silicon </li></ul><ul><li>Potassium </li></ul>
  38. 38. <ul><li>These two elements combine to form compounds called </li></ul>