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Observation & Inference

Observation & Inference. Look at the picture below. Write 3 observations. Based on your observations , come up with an inference . Chapter 4 Rocks and Minerals . LITHOSPHERE : Earth’s crust and the upper portion of mantle. Mineral Formation. 1) Minerals from Magma :

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Observation & Inference

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  1. Observation & Inference • Look at the picture below. • Write 3 observations. • Based on your observations, come up with an inference.

  2. Chapter 4Rocks and Minerals LITHOSPHERE : Earth’s crust and the upper portion of mantle

  3. Mineral Formation 1) Minerals from Magma: Convection of molten magma in mantle rising magma to surface cooling of lava (liquid ) Mineral ( Solid )

  4. 2) Minerals from Solution: Dissolved compounds in water Evaporation of water Precipitation of minerals

  5. Minerals • 3000 • Naturally occurring • Inorganic • Solid • Substance ( element, compound ) • Definite chemical composition and properties • Definite physical properties.

  6. Lab “Elements of the Earth’s Crust”

  7. Composition of Crust O, Si, Al, Fe, Ca, Na, K, Mg

  8. Mineral Groups INDICATORS Example • Silicates Si + O + element(s) SiO2 • Carbonates C + O + element(s) CaCO3 • Oxides O + metallic element(s) Fe2O3 • ( Fe, Mg, Al, Cu, Zn, … ) • Sulfates S + O + element(s) FeSO4 • Sulfides S + element(s) PbS • Phosphates P + O + element(s) NaH2PO4 • Halides ( F, Cl, Br, I ) + ( Na, K, Ca ) NaCl • Native Elements element Ag

  9. Practice Carbonate Sulfide • Underline the Indicator(s) and name the Mineral Group • Ca CO3 • Cu Fe S2 • Fe Al2 (SiO4)3 • Al O3 • Ca SO4 • Na Cl • Na PO3 • C • Ca F • Si O2 Silicate Oxide Sulfate Halide Phosphate Native Element Halide Silicate

  10. Mineral Groups Lab

  11. Observation & Inference

  12. Crystal unit • As compound cools/precipitates and solidifies atoms are pulled together at specific distances and angles. • Atomic arrangement creates a crystal unit. • As more of the compound solidifies, more atoms join the crystal unit crystal unit becomes larger. • Definite shape: Definite dimensions and angles between the atoms.

  13. Physical Properties Crystalline Structure: Solid, definite dimensions and angles Crystal Systems • Cubic or Isometric • Tetragonal • Hexagonal • Orthorhombic • Monoclinic • Triclinic

  14. Crystal Systems • 6 crystal models/ lab group • Color • Label • Cut, Fold & Tape • Poster • Crystal System Name • Mineral Example ff Crystal Systems --------------- ---------------

  15. a a a a a a a c a c a^a≠ 90° a^c = 90° All angles = 90° All angles = 90° Hexagonal Isometric/cubic Tetragonal a a a b b b c c c a^b= 90° All angles ≠ 90° All angles = 90° a & b ^ c ≠ 90° Orthorhombic Triclinic Monoclinic

  16. Examples of Crystal systems

  17. Physical Properties • Color External appearance of an object with respect to light reflected by the object, usually determined visually by measurement of hue and brightness of the reflected light. Color may vary due to the presence of trace elements (impurities). Ex. Quartz SiO2 Rose Quartz Fe, Ti Milky Quartz gas bubbles & liquids Smoky Quartz Al Obsidian Fe

  18. Obsidian

  19. Amethyst Fe2O3 Tiger eye Fe (Asbestos)

  20. Physical Properties • Luster • The state or quality of shining by reflecting light. • The way light is reflected from the surface of a mineral. • Metallic Ag, Au, Al, FeS2, PbS • Non-metallic • Quartz ( Si O2) Calcite ( Ca CO3) Hematite ( Fe2O3 )

  21. Physical Properties • Texture • Physical characteristic/quality of a surface. How it feels to the touch. smooth rough Obsidian Sandstone oily soapy Sulfur Talc

  22. Streak • True color of a mineral • In powder form • Streak does not change. • Gold Au Pyrite FeS2 • Fools Gold

  23. Obsidian

  24. Review • 1) Which physical property of minerals can change due to the presence of other elements? • 2) What can not be assumed about a mineral with a non-metallic luster? • 3) Describe the texture of your desktop. • 4) Compare and contrast gold and pyrite minerals in terms of • COLOR • STREAK

  25. Physical Properties • Hardness • A measure of the ease with which a smooth surface of a mineral can be scratched, or of its resistance to abrasion. • In 1822 the Austrian mineralogist Friedrich Mohs devised a scale based on one mineral's ability to scratch another. • Mohs Hardness Scale Relative hardness of a mineral

  26. Mohs Scale Finger nail 2.5 Glass 5.5 Steel nail 6.5 Streak plate 7

  27. FYI • What is the hardest mineral? • Diamond used to be the hardest mineral now Lansdaleite and wurtzite boron nitride which were found on a meteor are now harder.Read more: http://wiki.answers.com/Q/What_is_the_hardest_mineral#ixzz29W5pW4E3

  28. Physical Properties • Breakage • The breaking of mineral along atomic bonds. • Fracture: Irregular breaking • Bonds are uniformly strong throughout the mineral • Obsidian • Cleavage : Regular and defined breaks • Breakage along weaker bonds in the mineral • Mica

  29. Physical Properties • Special Properties • Physical property unique to a mineral. • Taste • Halite Na Clsalty • Smell • sulfur, sulfates, sulfides rotten egg smell Pyrite Fe S2 Galena Pb S

  30. Physical Properties • Special Properties Calcite • Chemical Reaction Calcite Ca CO3 reacts with HCl acid CO2 gas • Double Refraction • Calcite light is bent as it goes through double image

  31. Physical Properties • Special Properties • Magnetic Property Magnetite Fe2O3 • Malleability atomic bonds can be reshaped/bent without breaking. Au, Ag, Al, Cu, Fe

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