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Chapter 1 Minerals in the Earth’s Crust

Chapter 1 Minerals in the Earth’s Crust. SECTION 1. mineral. a naturally formed, inorganic solid that has a definite crystalline structure Must be able to say “yes” 1. must be a solid 2. must be a nonliving material 3. must have a crystalline structure

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Chapter 1 Minerals in the Earth’s Crust

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  1. Chapter 1Minerals in the Earth’s Crust

  2. SECTION 1

  3. mineral • a naturally formed, inorganic solid that has a definite crystalline structure Must be able to say “yes” • 1. must be a solid • 2. must be a nonliving material • 3. must have a crystalline structure • 4. must be formed in nature (not by man)

  4. elements • pure substances that cannot be broken down into simpler substances by ordinary chemical means

  5. compound • a substance made of two or more elements that have been chemically joined or bonded • NaCl = Sodium + Chlorine = salt • H2O = Hydrogen + Oxygen = water

  6. native element • a mineral composed of only one element Example: gold and silver

  7. General Facts about Minerals • Between 2 - 3,000 have been identified • A few are “native elements” -- made of only one element, such as sulfur, gold. copper, and graphite (carbon) • Most are compounds, especially the silicate group (Si, O). • Other important groups are oxides, carbonates, and sulfides.

  8. Less than a dozen are common in most rocks Olivine Amphibole (group) Magnetite, limonite, and other iron oxides Pyrite Quartz Feldspar (group) Muscovite (white mica) Biotite (black mica) Calcite Pyroxene

  9. Common uses include: • Aluminum--packaging, transport, building • Beryllium--gemstones, fluorescent lights • Copper--electric cables, wires, switches • Feldspar--glass and ceramics • Iron--buildings, automobiles, magnets • Calcite--toothpaste, construction • http://www.mii.org/commonminerals.php

  10. crystals • solid, geometric forms of minerals produced by a definite repeating pattern of atoms that is resent throughout the mineral

  11. silicate minerals • a mineral that contains a combination of silicon, oxygen and one or more metals • make up more than 90% of Earth’s crust • silicon and oxygen combine with other elements such as aluminum, iron, magnesium and potassium to make up silicate materials

  12. Common Silicate Minerals Feldspar KAlSi3O8 Mica Biotite K(Mg, Fe)3AlSi3O10(F, OH)2 Quartz Silicon Dioxide SiO2

  13. nonsilicate minerals • minerals that do not contain a combination of the elements silicon and oxygen • some made up of carbon, oxygen, fluorine and sulfur • native elements, oxides, carbonates, sulfates, halides & sulfides

  14. Classes of Nonsilicate Minerals Native Elements - composed of only one element. Gold Copper

  15. Classes of Nonsilicate Minerals Oxides - form when an element (such as aluminum or iron) combines chemically w/ oxygen. Corundum Al2O3 Aluminum oxide

  16. Classes of Nonsilicate Minerals Carbonates - contain combinations of carbon and oxygen in their chemical structure. Calcite CaCO3

  17. Classes of Nonsilicate Minerals Sulfates - contain sulfur and oxygen, SO4. Gypsum Calcium Sulfate Dihydrate CaSO4·2H2O

  18. Classes of Nonsilicate Minerals Halides - form when: flourine, chlorine, iodine, or bromine combine with sodium, potassium, or calcium Flourite Calcium Fluoride CaF2

  19. Classes of Nonsilicate Minerals Sulfides - contain one or more elements (such as lead, iron, or nickel) combined with sulfur. Galena Lead Sulfide PbS

  20. SECTION 2

  21. Minerals are identified by their key characteristics • hardness • crystal shape (form) • luster • color • streak • cleavage/fracture • density (specific gravity) • special properties --reaction to acid --fluorescence --salty taste --magnetism

  22. COLOR • results from ability to absorb some wavelengths and reflect others • some minerals have characteristics colors • others vary due to chemical differences or impurities (atoms mixed inside the main elements) • because of factors such as impurities, color is not the best way to identify a mineral

  23. COLOR

  24. LUSTER • Describes how light reflects off the surface • “shiny” = metallic luster • “dull” = submetallic or nonmetallic luster

  25. STREAK • Color of the powder when rubbed on a “streak plate” (unglazed porcelain) • can be found by rubbing the mineral against a piece of unglazed porcelain • powdered color is not always the same color of the mineral sample

  26. Streak Plate = a piece of unglazed porcelain used to test the streak of minerals

  27. Submetallic - dull, reflective Euxenite

  28. Nonmetallic Vitreous glassy, brilliant Pollucite

  29. Nonmetallic Silky fibrous Gypsum

  30. Nonmetallic Resinous plastic Sphalerite

  31. Nonmetallic Waxy greasy, oily Cancrinite

  32. Nonmetallic Pearly creamy Stellerite

  33. Nonmetallic Earthy rough, dull Kaolinite

  34. Cleavage of mica into thin sheets Cleavage = the tendency of some minerals to break along smooth, flat surfaces

  35. Cleavage in calcite

  36. fracture in obsidian fracture = the tendency of some minerals to break unevenly along curved or irregular surfaces

  37. HARDNESS • a mineral’s resistance to being scratched • the greater a mineral’s resistance to being scratched, the higher the rating • Mohs scale from 1 (talc) to 10 (diamond) • Quartz (most common mineral and most dust particles) is 7

  38. MOHS HARDNESS SCALE

  39. DENSITY (Specific Gravity) • All minerals have density (mass / volume), but some are very dense • Examples include galena, magnetite, and gold • Specific Gravity is the density of the mineral compared with density of water

  40. SPECIAL PROPERTIES • particular to only a few types of minerals – need specialized equipment to determine these properties EXAMPLES: fluorescence, chemical reaction, optical properties, magnetism, taste, radioactivity

  41. Special Property - Fluorescence • Some minerals will glow when placed under short-wave or long-wave ultraviolet rays • Franklin and Ogdensburg NJ are famous for their fluorescent minerals Calcite (red) and willemite (green)

  42. Special Property -Salty Taste • DO NOT TASTE MOST MINERALS! Halite is the exception--it will taste salty Borax tastes sweet.

  43. Special Property -Magnetism • Many iron minerals will produce an invisible magnetic force field • “Lodestone” was used by Vikings more than 1,000 years ago as compasses

  44. Special Property - Radioactivity Autunite contains uranium.

  45. Special Property - Chemical reaction carbonatesreact with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas) • CaCO3 + 2HCl = CO2 + H2O + CaCl2 calcite hydrochloric acid

  46. Special Property - Optical properties such as double refraction. Same sample of calcite, but it’s rotated.

  47. SECTION 3

  48. Evaporating Salt Water • when a body of salt water dries up/evaporating these minerals crystallize • Examples = gypsum and halite

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