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nOTES : Mineral identification

nOTES : Mineral identification. The pictures seen here are of the mineral Fluorite. The pieces have different colors, sizes, and crystal shapes, but they are all still Fluorite. How is this possible?. Fluorite occurs in many colors, even colorless.

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nOTES : Mineral identification

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  1. nOTES: Mineral identification

  2. The pictures seen here are of the mineral Fluorite. • The pieces have different colors, sizes, and crystal shapes, but they are all still Fluorite. • How is this possible?

  3. Fluorite occurs in many colors, even colorless. • Its crystals can be large or small, smooth or rough.

  4. If you came across fluorite while hiking, would you know what it was just by looking at it? Probably not. • Today we will learn how you could identify it.

  5. To identify a mineral, you need to look at its properties-features or qualities that identify it.

  6. Most minerals have a limited color range. Color

  7. 3 causes for minerals to come in different colors… Color

  8. 1. Impurities-tiny amounts of an element that is not normally part of the mineral gets inside. Color

  9. Example: Pure quartz is colorless. • Tiny amounts of iron turns quartz purple (amethyst). Color

  10. 2. The mineral comes into contact with the atmosphere or water. Color

  11. 3. Different crystal shapes can change the color. • Example: Hematite with small crystals looks dull. • Hematite with large crystals looks shiny. Color

  12. Some minerals have a different color when they are ground into a powder than when they are whole. Color

  13. Streak is the color left behind when a mineral is scraped across a surface or ground into a powder. Color

  14. Scientists use a piece of porcelain called a streak plate to help identify minerals Color

  15. Streak is a better clue to a mineral’s identity than surface color. streak

  16. All samples of the same mineral have the same streak. streak

  17. Luster is the way light reflects off a mineral’s surface. luster

  18. Metallic luster-looks like it’s made of metal. • Pyrite (Fool’s Gold) has metallic luster. luster

  19. Nonmetallic luster-looks shiny, but not metallic. luster

  20. Minerals always break in the same way. Cleavage and fracture

  21. Calcite breaks into blocks. • Mica splits into thin, flat sheets. Cleavage and fracture

  22. Cleavage is when a mineral breaks along flat surfaces. Cleavage and fracture

  23. Minerals with cleavage have weak bonds between their atoms along the lines where they break. Cleavage and fracture

  24. Fracture is when a mineral breaks into irregular pieces. Cleavage and fracture

  25. Minerals with fracture have atomic bonds that are equal in all directions. • The mineral will not break along flat surfaces. • Example: Quartz breaks by fracturing. Cleavage and fracture

  26. Imagine you close your eyes and someone handed you a tennis ball and a baseball. • You would be able to tell the two apart without looking. • Minerals can also be identified in the same way. Density and hardness

  27. What weighs more, a pound of bricks or a pound of feathers? density

  28. What takes up more space, a pound of bricks or a pound of feathers? density

  29. The bricks are more dense; they have more density! Density

  30. Density-the amount of mass in a given volume of a substance. density

  31. Example: 1 cm3 of pyrite has a mass of 5.1 grams. • Its density is 5.1 g/cm3 density

  32. The density of a mineral is helpful to identify it. • Gold is more dense than pyrite (Fool’s Gold). density

  33. Hardness-a mineral’s resistance to being scratched. hardness

  34. The Mohs scale is used to describe mineral hardness. • Talc is the softest with a value of 1 and Diamond is the hardest with a value of 10. hardness

  35. You can test the hardness of minerals by the items they are or are not able to scratch. Hardness

  36. Some minerals have extra special properties that can help identify them. special properties

  37. Minerals in the carbonate group react with acid. special properties

  38. Fluorescent minerals glow under UV light. special properties

  39. How is it possible for two different minerals to have the same chemical composition? • They have different crystal structures. • One is formed only by organisms. • Only one is a rock-forming mineral. • They have different appearances. Review

  40. 2. Which of the following is the least reliable clue to a mineral’s identity? • Color • Density • Hardness • Luster review

  41. 3. Many properties of a mineral are related to the • Number of elements of which it is made. • Other types of minerals present as it formed. • Strength of bonds between its atoms • Speed at which it formed. review

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