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Chapter 4

Chapter 4. Mineral Identification BFRB P. 192-195. Key Ideas. “Rock Forming” minerals are the most common substances found in earth’s crust Minerals are identified by their PHYSICAL PROPERTIES VIF - Physical properties are determined by the ATOMIC ARRANGMENT of atoms!

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Chapter 4

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  1. Chapter 4 Mineral Identification BFRB P. 192-195

  2. Key Ideas • “Rock Forming” minerals are the most common substances found in earth’s crust • Minerals are identified by theirPHYSICAL PROPERTIES • VIF - Physical properties are determined by theATOMIC ARRANGMENTof atoms! • The study ofminerals & their physical properties is called mineralogy

  3. Use your Handy Dandy ESRT’s Page 16 when identifying an unknown mineral!

  4. Physical Characteristics The following characteristics may be observed by just using our sense of sight…

  5. Crystal Shape • The shape of the mineral’s crystals are a result of its atomic arrangement - VIF!!! • All of a minerals physical properties are also a result of its atomic structure!!!

  6. Identification bySIMPLE TESTS Because we can’t identify minerals on their outward appearance alone, we have to perform some simple tests to prove what the mineral is beyond a shadow of a doubt….

  7. Metallic It has the appearance of metal Non-metallic Waxy, greasy Pearly, translucent Transparent Opaque Earthy Glassy Dull Vitreous Luster

  8. Hardness Talc • A mineral’s resistance to being scratched • MOH’s hardness scale 1-10 • Tools for hardness test: • Fingernail • Copper penny • Steel nail • Glass plate • Streak plate Diamond

  9. cleavage Even, smooth surface(s) (clean breaks) fracture Uneven surfaces (bumpy) Breakage How does the mineral look when it breaks?

  10. Examples of the planes that cause cleavage. The planes are caused by the minerals’ atomic arrangements. Remember… crystals

  11. Color • The outward appearance of the mineral • This property alone can’t be used to ID a mineral because…. • FLAW #1 – different minerals can have the same color • FLAW #2 – the same mineral can be different colors!

  12. The Many Colors of Fluorite

  13. Streak • The color of a mineral’s powder left behind after scratching a “streak plate”

  14. Other Mineral Properties & Special Identifying Characteristics

  15. Specific Gravity • A comparison between the weight of a mineral and the weight of an equal VOLUME of water • Specific gravity is essentially the same thing as density. Because you’re comparing the mineral to water, which has a density of 1.0 g/cm3

  16. Specific Gravity • What’s different is that Specific Gravity DOES NOT HAVE ANY UNITS ASSOCIATED WITH IT!!!!! • Ex. Density of aluminum = 2.7 g/cm3 • Density of water = 1.0 g/cm3 • SG = Density of substance Density of water • SG = 2.7 g/cm3 1.0 g/cm3 SG of Aluminum = 2.7 NO UNITS!!!!!!! (because they cancel out…)

  17. Acid Test • Certain minerals react (bubble) withhydrochloric acid(HCl) • A great way of identifyingCALCITE!

  18. Special properties of some minerals • Certain minerals are easily identified by special properties • Fluorite: glows under a black light • Sulfur: bright yellow color, rotten egg smell • Calcite: double refraction, reacts with HCl • Halite: tastes like salt • Magnetite: is magnetic (duh…)

  19. There are Two Dominant Families in the World of Minerals (no, not The Sopranos…)

  20. The Silicates • These minerals contain the elements silicone and oxygen in a ratio of 1:4 (1 silicone surrounded by 4 oxygens) • These minerals contain the silica tetrahedron • Quartz • Feldspar • Mica • Talc • Amphibole • Pyroxene

  21. Iron Oxides & Iron Sulfides • Certain minerals contain a large amount of iron. • When these minerals combine withOxygen,the result isIRON OXIDE(rust) • Ex Hematite, Magnetite • When these minerals combine withSulfur,the result isIRON SULFIDE • Pyrite

  22. Remember… just in case I hadn’t mentioned it before… Your ESRT Pg. 16 lists all the mineral information you will need to identify an unknown mineral sample!

  23. And there was much rejoicing…

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