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Minerals

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  1. Minerals

  2. Minerals • Naturally occurring • Inorganic • Crystalline solid (atoms are arranged in a repeating pattern) • Definite chemical composition

  3. Why do we study Minerals? • Starting point for all geologic formations and activity • Rocks and molten rock (lava, magma) are what shape the surface of our planet

  4. Single elements that are also minerals are called native elements (ex: copper) Most minerals are compounds made from different elements 8 most common elements: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium Minerals Can Be Elements or Compounds

  5. How Minerals Form • The cooling and hardening of magma • When water containing dissolved ions evaporate • Sustained pressure, heat, or chemical action can change minerals into other minerals

  6. Mineral’s Crystalline Structure • All minerals are crystalline (all of their atoms are arranged in a repeating pattern) • The atoms pattern can be used to identify a mineral • Crystal system controls the way a mineral forms and breaks

  7. Crystal System Models • Color the shapes according the colors listed below. A:Red B: Blue C: Green D:Yellow E: Orange F: White • Cut them out • Fold them along all the black lines • Put glue on the small tabs and CAREFULLY glue them into the shapes they fold into. • You will need the small images of the crystals. Cut them and secure them in a safe place. Do NOT lose them!

  8. The 6 Crystal Systems: #1 • Cubic System • 3 axes of equal length that intersect at 90 degree angles • Example • Halite (Rock Salt)

  9. The Six Crystal Systems #2 • Orthorhombic System • Three axis of different length that intersect at 90 degree angles • Examples: • Sulfur, Topaz

  10. The Six Crystal Systems #3 • Tetragonal System • Three axes, 2 of the same length, one that differs • Examples: • Wulfenite

  11. The Six Crystal Systems #4 • Triclinic System • Three axes of unequal length that intersect at oblique angles. • Example: • Turquoise

  12. The Six Crystal Systems #5 • Hexagonal System • Three horizontal axes that are the same length, and a vertical axis that is longer then the horizontal axes. • Example: • Quartz • Graphite

  13. The Six Crystal Systems #6 • Monoclinic System • Three unequal axes, two intersect at 90 degrees, the third is oblique to the other two • Example: • Gypsum, Borax

  14. Physical Properties • Color: The color as it appears to the naked eye • Not effective in identifying minerals • Some are similar in color • Others can have their color changed • Some come in multiple colors

  15. Physical Properties • Streak:the color of the powder a mineral leaves after rubbing it on a streak plate. • More effective than color because the streak is often different than the color, and can be distinct to the mineral

  16. Properties Cont’d • Luster: the way a mineral shines and reflects light • Metallic Luster: Shines like a polished metal • Ex: Pyrite, Galena, Hematite, Magnetite • Non-Metallic: Anything non-metallic. • Ex: Quartz, Fluorite, Sulfur, Opal

  17. Hardness: A mineral’s resistance to being scratched Moh’s Hardness Scale: The hardness of minerals relative to each other/scratching implements. These are labeled 1-10, 1 being the softest, 10 the hardest. Mohs Hardness Scale

  18. Cleavage • Cleavage: the tendency of a mineral to split along a certain plane or planes • Not all minerals have cleavage • We describe it in numbers of planes and angles of intersection

  19. Fracture • Fracture: When minerals don’t break along certain planes 3 KINDS • Conchoidal: Shell Like and smooth • Hackly: Jagged Edges • Fibrous: Breaks into strands

  20. Special Properties • Texture: Having a unique feel to the touch (talc, graphite) • Effervescence: Reacts by bubbling when exposed to hydrochloric acid (calcite, dolomite) • Taste: What does it taste like?… Duh… (Halite/Rock Salt)

  21. Special Properties Cont’d • Smell: (Sulfur smells like eggs) • Magnetism: Mineral has magnetic properties (Magnetite) • Density: the amount of water it displaces (Metallic lusters are generally denser) • Phosphorescence: Does it glow under black light? (Fluorite)

  22. Today = Finish Dummies Guide • Make sure all information is complete. • All charts and test are complete. • Accurately identify minerals A, B, C, D using your notes and classification chart.

  23. The Silicates • Silicates: Compound of the elements Silicon and Oxygen • 90% of minerals are silicates • Form from the cooling of Lava/Magma • The Si and O join to form Silicon-Oxygen Tetrahedrons

  24. Silicate Minerals: Quartz: • Multiple forms of quartz (rose, amethyst, crystal) • Conchoidal Fracture • Mohs Hardness: 7 • Luster: Glassy

  25. Silicate Minerals Continued… Feldspar: • The most abundant family of minerals in earth crust • Plagioclase or Orthoclase Feldspar • 2-3 directions of cleavage • Mohs Hardness: 6 • Luster: Pearly

  26. Silicate Minerals Continued… Mica 2 Types • Muscovite mica (white mica), and Biotite mica (black or brown) • One distinct Cleavage (makes long sheets) • Mohs Hardness: 2.5 • Luster:Pearly

  27. Silicate Minerals Continued… Talc • The softest mineral, talcum powder is pure ground up talc • 1 direction of cleavage • Mohs Hardness: 1 • Luster:Pearly/Oily

  28. Silicate Minerals Continued… Olivine: • Olive green silicate • Belongs to a family where silicates bond to metal ions, ocassionally found in meteors • Conchoidal Fracture • Mohs Hardness: 6.5 • Luster: Glassy

  29. Silicate Minerals Continued… Garnet: • A very common gemstone • Conchoidal Fracture • Hardness: 6-7.5 • Luster: Vitreous to resinous

  30. Other Mineral Groups • Carbonates • 2nd most common mineral group • Contains the elements carbon and oxygen and one or more other metallic elements • EX. Calcite, Dolomite

  31. Carbonate Minerals Calcite: • Composed of Calcium Carbonate (CaCO3) • CALCITE FIZZES WITH ACID!!! • 3 directions of cleavage • Mohs Hardness: 3 • Luster: Glassy

  32. Carbonate Minerals Dolomite: • Composed of a Magnesium Carbonate (MgCO3) • 3 directions of cleavage • Mohs Hardness: 3.5 to 4.0 • Luster: Glassy/Vitreous

  33. Other Mineral Groups • Halides: • Contain a halogen ion plus one of more elements • Formed from salt water evaporation • EX. Halite, Fluorite

  34. Other Mineral Groups • Sulfides/ Sulfates: • Contain the element sulfur and one other element, often metallic • EX. Gypsum, Pyrite

  35. Bellringer Quiz • 1. ______The way a mineral reflects or “reacts” to light • 2. ______A mineral’s resistance to being scratched • 3. ______ Includes taste, effervesence, smell, phosphorescence • 4. ______Describes the way minerals naturally split • 5. ______The color of a minerals powder when rubbed across an unglazed porcelain plate • 6. ______When minerals don’t break along cleavage lines • 7. ______Considered to be a not-reliable way to I.D. minerals • 8. Define mineral! • 9. Why are color AND luster unreliable for IDing minerals?

  36. Other Mineral Groups • Oxides: Contain oxygen and one or more other element usual a metal. • Can form from magma or from weathering • EX. Hematite (Rust), Corundum, Magnetite

  37. Other Mineral Groups • Native Elements:elements that exists in relative pure forms • Many form from hydrothermal solutions • EX. Diamond and Graphite (carbon), silver, gold, copper, sulfur

  38. Mineral uses • Talc – talcum powder • Quartz – Glass, Sand Paper, Amethyst Gems • Diamond – Gems, drills • Beryl – Emerald Gems • Corundum – Ruby Gems • Gypsum – Drywall • Halite – Rock Salt • Copper – Wire, Jewelry, etc… • Galena - Lead ore

  39. Bellringer Picture

  40. Iron Oxide and Sulfates Oxides -A mineral consisting of a metal element combined with oxygen Sulfates -A mineral consisting of a metal element combined with sulfur

  41. Iron Oxide Minerals Hematite • The most common Iron Oxide mineral • Red to brown streak on streak plate • Mohs Hardness: 5 to 6 • Luster:Metallic (sometimes earthy if it gets worn down)

  42. Iron Oxide Minerals Magnetite: • A black magnetic iron oxide • Mineral has magnetic properties • Black streak • Mohs Hardness: 5.5 to 6.5 • Luster: Metallic to Dull

  43. Iron Sulfides Pyrite: • An Iron Sulfide (Fe3SO4) • Occurs in 6 and 12 sided crystals • “Fools Gold” • Greenish-Black streak • Mohs Hardness: 6.0 • Luster: Metallic