The document summarizes key concepts from chapters 4-6 about rocks and minerals. It defines minerals as naturally occurring inorganic solids with specific chemical compositions and crystalline structures. It describes the formation of igneous, sedimentary, and metamorphic rocks and how their characteristics are influenced by cooling rates, pressure, heat, and other factors. Identification properties of minerals like color, luster, hardness, and cleavage are also outlined.

1. Rocks and Minerals Chapters 4 - 6

2. Mineral Naturally Occurring Inorganic Solid Specific chemical composition Definite crystalline structure

3. Naturally Occurring & Inorganic Formed in nature Natural diamonds are minerals Synthetic diamonds are not Inorganic Are not alive, and never was alive

4. Question: Is coal a mineral?

5. Composition Solid Definite Composition – Made up of specific compounds or elements Copper (Cu), Gold (Au), Silver (Ag) Salt (NaCl), Quartz(SiO 2 ) Sometimes composition varies slightly (ex : yellow diamonds)

6. Crystalline structure Crystal – Solid in which atoms are arranged in repeating patterns. Atomic Viewer Minerals form in open spaces and crystals grow to fill the space

7. Crystal systems

8. Mineral Formation Magma – As magma cools, the compounds can no longer move freely and chemically interact to form minerals. If magma cools too quickly, you will have no crystals. Solution – If supersaturated, minerals will precipitate. Evaporation – if water evaporates solutions become supersaturated

9. Mineral Groups Silicates (SiO 4 ) Most abundant type of mineral (~96%) Ex : Feldspar, Quartz Tetrahedral Shape (pg 82)

10. Carbonates Carbonates (CO 3 ) – Commonly contains metal bonded with CO 3 , combines easily with other minerals. Ex : Limestone, Marble and Malachite

11. Oxides Oxide – Metal and oxygen. ex : Hematite and magnetite

12. Other mineral groups Sulfides (Element + S 2 ) Sulfate (Element + SO 4 ) Halides (Element + Halide) – NaCl Native element (just an element)

13. Mineral Identification Color – Caused by trace elements or compounds within a mineral Least reliable clue to mineral identity Luster – The way a mineral reflects light Metallic minerals reflect light Non-metallic do not shine Dull, pearly, waxy or silky

14. Mineral Identification Cont’d Texture – How minerals feel to the touch. smooth, rough, ragged, greasy, soapy, glassy

15. Mineral Identification cont’d Streak – The color of a mineral when it is broken up and powdered.

16. Mineral Identification cont’d Hardness – Measure of how easily a mineral can be scratched. Moh’s Scale 1 – 10 uses basic items that can be carried anywhere (finger nail, iron nail, glass, streak plate)

17. Mineral Identification cont’d Minerals break along planes where atomic bonding is weak (mica) Cleavage – A mineral that splits evenly along planes Fracture – Minerals that break with rough or jagged edges

18. Mineral Identification cont’d Density – Reflects atomic weight and structure of mineral D = M / V Specific Gravity – Measure of density using water Special properties Ex : Double refraction - Calcite

19. Mineral Uses Ores – Mineral that can mined for a profit. Ex : Hematite  Iron Ex : Bauxite  Aluminum Gems – Valuable minerals prized for rarity and beauty. Ex : Rubies and Sapphires, both corundum with trace minerals Under Sea Deposits No owners  international law Not enough technology Destroy oceans

20. Rocks: Mixture of minerals

21. Igneous Rocks Formed from the cooling of magma Crystallization- formation of crystals Ignis- Latin-”fire” Types Intrusive- cool slowly under Earth’s surface, large crystals Extrusive- cool quickly above Earth’s surface, small/no crystals

22. Composition of Magma Slushy mixture of molten rock, gases, and mineral crystals Contain Elements: O, Si, Al, Fe, Mg, Ca, K, and Na Silica (SiO 2 ) is most abundant What factors affect magma???

23. Origins of Magma Rocks melt between 800-1220 °C Found in upper mantle or lower crust Geothermal gradient (temperature increase with depth) p101

24. Melting Temperatures Affected by water content, silica content, Type of mineral in magma Oceanic Crust melts at higher temp, than continental crust  b/c high magnesium and iron, low in water Partial Melting- Not all parts of a rock melt at the same time  different minerals are added to magma at different times, changing type of rock formed

25. Melting Temperatures Cont’d Fractional Crystallization- magma cools and crystallizes in reverse order form melting Removing minerals form the magma

26. Bowen’s Reaction Series Predictable pattern of magma cooling Feldspars (calcium rich) change composition to sodium rich rocks gradually Iron-Rich rocks change stepwise with fractional crystallization Rocks form in order of Bowen’s

27. Crystal Separation Since Olivine changes to pyroxene during cooling, why is found in nature at all? Crystal Separate from magma, preserving olivine

28. Layered Intrusions Sometimes magma cools in layers. These “layered intrusions” often have valuable sources of rare metals

29. Classifying Igneous Rocks Intrusive/Extrusive Mineral Composition Felsic- light colored, high silica, Contain Quartz and Feldspars Ex: Granite Mafic- dark in color, lower silica, rich in iron and magnesium Ex: Olivine, Amphibole Ultra-Mafic-Very low silica and very high iron, Magnesium

30. Classifying Igneous Rock Cont’d Grain size- dependant on cooling rate (fast-smaller) Glassy- Cools very quickly, think air or water cooling lava off

31. Grain Size Fine Grain- Fast cooling Course Grain- Slow cooling Porphyritic- Both fast and slow cooling

32. Igneous Rocks as Resources Useful building materials  interlocking crystals give strength Resists weathering Ore Deposits  often found in igneous intrusions Veins- Left-overs from Bowen/s Reactions are often valuable gems (gold, silver, lead, copper) Pegmatites- Veins of very large grain minerals (ores and gemstones)

34. Diamonds Kimberlites- ultra mafic rock that diamond is found in Found 150-300 Km depth (need VERY high pressure)

35. Buying Diamonds Color- Range from D-Z (D being colorless and Z being bright yellow J and K are great bargains! Clarity Inclusions- Imperfections inside crystal VS 1-2 even SI 1 good deals

36. Buying diamonds Cut- Many ways of cutting Beware of brand cuts Carat Weight- Size by weight of your gem ½ carat diamond about $1,500

37. Sedimentary Rocks Sediments- pieces of solid material deposited by wind, water, ice, gravity or chemical precipitation Weathering- breaking down by physical and chemical processes Produces clastic pieces  “broken pieces” Erosion- transport of rock (rain, ice) Deposition- sediment laid down or sinks to bottom

38. Erosion/Deposition

39. Formation of Sedimentary Rocks Lithification- process by which sediments turn to rocks Must have thick layers of sediment, increasing pressure and temperature Cementation- a chemical process which mineral growth solidifies sediments

40. Features of Sedimentary Rocks Bedding- horizontal rock layers Graded- large particles fall to bottom Cross- inclined layers move across a horizontal surface (sand dune)

41. Features of Sed. Rocks Cont’d Fossils Patterns-- waves

42. Types Clastic- Course Grain- Round- Conglomerate Angular- Breccia Medium Grain Sandstone-filters drinking water Porosity- % of open spaces Fine grain- Siltstone- traps water

43. Types Cont’d Chemical- Evaporites- formed from evaporation Salts Organic- remains of once living organisms Limestone Coal

44. Metamorphic Rocks Rocks that are changed Meta-change Morphe-form Forces- Heat and Pressure

45. Types of Metamorphism Regional- When Heat/pressure affect large regions or bands

46. Types of Metamorphism Cont’d Contact (touch)- Edges of batholith touch an area changing the rocks

47. Types of Metamorphism Cont’d Hydrothermal- Hot water (near volcanoes change rock) ex: Brimstone

48. Metamorphic Textures Foliated- wavy bands of crystals Gneiss (formerly granite) Non-Foliated- no visible layers

49. Rock Cycle