WHS ES- Minerals

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WHS ES- Minerals

  1. 1. So what is a mineral?So what is a mineral? What are the characteristics ofWhat are the characteristics of all minerals?all minerals?
  2. 2. 1. A mineral occurs naturally.1. A mineral occurs naturally.
  3. 3. 2. A mineral is solid.2. A mineral is solid.
  4. 4. 3. A mineral has a definite chemical3. A mineral has a definite chemical composition.composition.
  5. 5. 4. A mineral’s atoms are arranged4. A mineral’s atoms are arranged in an orderly pattern.in an orderly pattern.
  6. 6. 5. A mineral is inorganic (was never5. A mineral is inorganic (was never alive)alive)
  7. 7. Approximately 4000 known mineralsApproximately 4000 known minerals About 30 are commonAbout 30 are common The most common areThe most common are quartz,feldspar,mica, and calcite.quartz,feldspar,mica, and calcite.
  8. 8. These minerals make up most ofThese minerals make up most of the rocks found in the Earth’sthe rocks found in the Earth’s crust.crust.
  9. 9. In fact, overIn fact, over 60%60% of the Earth’sof the Earth’s crust is made up of the family ofcrust is made up of the family of minerals known as feldspar!minerals known as feldspar!
  10. 10. To be able to identify these andTo be able to identify these and other minerals, we need to look atother minerals, we need to look at thethe propertiesproperties used to separateused to separate and distinguish these minerals.and distinguish these minerals.
  11. 11. Remember!:Remember!: Rarely is a mineral identified by aRarely is a mineral identified by a single property.single property. These properties need to beThese properties need to be considered together to correctlyconsidered together to correctly identify a mineral.identify a mineral.
  12. 12. Color is the most easily observedColor is the most easily observed mineral property and themineral property and the leastleast useful!useful!
  13. 13. Many minerals have a similarMany minerals have a similar color.color.
  14. 14. Many minerals can turn colors dueMany minerals can turn colors due to impurities, or they can changeto impurities, or they can change colors in various circumstances.colors in various circumstances.
  15. 15. For example, pure quartz is colorlessFor example, pure quartz is colorless or white, impurities can make theor white, impurities can make the mineral rose, purple or pink!mineral rose, purple or pink!
  16. 16. Some exceptions to the color ruleSome exceptions to the color rule would bewould be cinnabarcinnabar, which is, which is always red, andalways red, and malachitemalachite, which, which is green.is green.
  17. 17. Discuss the following!Discuss the following! How many of the characteristicsHow many of the characteristics of minerals can you name?of minerals can you name? Why isn’t color a very goodWhy isn’t color a very good property to identify mostproperty to identify most minerals?minerals?
  18. 18. Luster refers to the way a mineralLuster refers to the way a mineral shines in reflected light.shines in reflected light. Notice the difference betweenNotice the difference between these two minerals?these two minerals?
  19. 19. The mineral on the left has aThe mineral on the left has a metallic lustermetallic luster, the one on the, the one on the right, aright, a nonmetallic lusternonmetallic luster..
  20. 20. There are several terms used toThere are several terms used to describe nonmetallic luster. Examplesdescribe nonmetallic luster. Examples could becould be vitreousvitreous, like the quartz on, like the quartz on the left, orthe left, or pearlypearly, like the gypsum on, like the gypsum on the right.the right.
  21. 21. Other terms that might be used includeOther terms that might be used include greasy, dull,greasy, dull, andand earthyearthy.. Can you tell which of these has anCan you tell which of these has an earthy luster and which has a vitreousearthy luster and which has a vitreous luster?luster? Earthy Vitreou s
  22. 22. StreakStreak of a mineral is the color of itsof a mineral is the color of its powder when rubbed on anpowder when rubbed on an unglazed white tile.unglazed white tile.
  23. 23. The streak is often not the sameThe streak is often not the same color as the mineral.color as the mineral. A minerals color may vary, but theA minerals color may vary, but the streak rarely will!streak rarely will!
  24. 24. TheThe cleavagecleavage of a mineral is itsof a mineral is its tendency to split easily or totendency to split easily or to separate along flat surfaces.separate along flat surfaces. Cleavage can even be observed onCleavage can even be observed on tiny mineral grains making it a verytiny mineral grains making it a very useful property!useful property!
  25. 25. MicaMica is probably the best example asis probably the best example as it splits into thin sheets. It is said toit splits into thin sheets. It is said to have one perfect cleavage.have one perfect cleavage.
  26. 26. FeldsparFeldspar splits readily in twosplits readily in two directions, always at or near rightdirections, always at or near right angles.angles.
  27. 27. CalciteCalcite andand galenagalena cleave in threecleave in three directions.directions. They are said to have three goodThey are said to have three good cleavages.cleavages.
  28. 28. Not all minerals show cleavage.Not all minerals show cleavage. Those that don’t break along cleavageThose that don’t break along cleavage surfaces are said to havesurfaces are said to have fracturefracture..
  29. 29. Discuss the following!Discuss the following! There are four common minerals,There are four common minerals, how many can you name?how many can you name? Of the four common minerals,Of the four common minerals, which one makes up over 60% ofwhich one makes up over 60% of the Earth’s crust?the Earth’s crust?
  30. 30. TheThe hardnesshardness of a mineral is itsof a mineral is its resistance to being scratched.resistance to being scratched. Diamond is the hardest of allDiamond is the hardest of all minerals, and talc is the softest.minerals, and talc is the softest.
  31. 31. FriedrichFriedrich MohsMohs devised a hardness scale.devised a hardness scale. In this scale, ten well-known minerals areIn this scale, ten well-known minerals are given numbers from one to ten.given numbers from one to ten. Lets take a look at the ten minerals usedLets take a look at the ten minerals used and some of the simple tests.and some of the simple tests.
  32. 32. TalcTalc (left) is the softest and has a hardness(left) is the softest and has a hardness of 1. A soft pencil lead will scratch talc.of 1. A soft pencil lead will scratch talc. GypsumGypsum is a bit harder and has a hardnessis a bit harder and has a hardness of 2. A fingernail scratches gypsum.of 2. A fingernail scratches gypsum.
  33. 33. CalciteCalcite (left) has a hardness of 3 and a(left) has a hardness of 3 and a copper penny just scratches it.copper penny just scratches it. FluoriteFluorite has a hardness of 4 and it canhas a hardness of 4 and it can be scratched by an iron or brass nail.be scratched by an iron or brass nail.
  34. 34. ApatiteApatite (left) has a hardness of 5 and(left) has a hardness of 5 and can be scratched by a steel knifecan be scratched by a steel knife blade.blade. FeldsparFeldspar has a hardness of 6 and it willhas a hardness of 6 and it will scratch a window glass.scratch a window glass.
  35. 35. QuartzQuartz (left), with a hardness of 7, is the(left), with a hardness of 7, is the hardest of the common minerals. It easilyhardest of the common minerals. It easily scratches hard glass and steel.scratches hard glass and steel. TopazTopaz has a hardness of 8 and will scratchhas a hardness of 8 and will scratch quartz.quartz.
  36. 36. CorundumCorundum (left) has a hardness of 9.(left) has a hardness of 9. Corundum will scratch topaz.Corundum will scratch topaz. DiamondDiamond with its hardness of 10 can easilywith its hardness of 10 can easily scratch the rest of the minerals.scratch the rest of the minerals.
  37. 37. Discuss the following!Discuss the following! Does this mineral show cleavageDoes this mineral show cleavage or fracture?or fracture? Of the four most commonOf the four most common minerals, which is the highestminerals, which is the highest hardness?hardness?
  38. 38. Crystal shapeCrystal shape can be a usefulcan be a useful property to identify minerals if theproperty to identify minerals if the minerals have had the time andminerals have had the time and space to form crystals. Mostspace to form crystals. Most mineral grains that are found inmineral grains that are found in rocks, lack the room to grow.rocks, lack the room to grow.
  39. 39. Specific gravitySpecific gravity tells you how manytells you how many times as dense as water the mineraltimes as dense as water the mineral is.is. Pure gold can have a specific gravityPure gold can have a specific gravity as high as 19.3!as high as 19.3!
  40. 40. Malleable Magnetic Radioactiv e Flourescence Taste
  41. 41. CalciteCalcite is calcium carbonate, CaCOis calcium carbonate, CaCO33.. If a drop of weak hydrochloric acidIf a drop of weak hydrochloric acid is placed on calcite, the acidis placed on calcite, the acid bubbles as carbon dioxide isbubbles as carbon dioxide is released.released.
  42. 42. Minerals that can be hammered thin orMinerals that can be hammered thin or shaped are said to show theseshaped are said to show these properties.properties. Can you think of a mineral that might beCan you think of a mineral that might be shaped or hammered?shaped or hammered?
  43. 43. GoldGold would be a perfect example!would be a perfect example!
  44. 44. Some mineralsSome minerals that contain Iron,that contain Iron, are magnetic andare magnetic and can be picked upcan be picked up by a magnet.by a magnet.
  45. 45. This is the state ofThis is the state of glowing while under aglowing while under a ultraviolet light.ultraviolet light. Some minerals evenSome minerals even glow once the light isglow once the light is turned off!turned off!
  46. 46. Some minerals, suchSome minerals, such as thisas this uraniniteuraninite, are, are radioactive.radioactive. They give offThey give off subatomic particlessubatomic particles that will activate athat will activate a Geiger counterGeiger counter..
  47. 47. HaliteHalite (rock salt)(rock salt) can be identifiedcan be identified by its taste.by its taste. This practice is notThis practice is not recommended!recommended!

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