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CHAPTER 9: MINERALS OF THE EARTH’S CRUST

CHAPTER 9: MINERALS OF THE EARTH’S CRUST. What is a mineral?. A mineral: is inorganic is naturally occurring is a crystalline solid has a definite chemical composition. to 9.1. Inorganic?. Inorganic means that it is not made by a living organism .

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CHAPTER 9: MINERALS OF THE EARTH’S CRUST

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  1. CHAPTER 9: MINERALS OF THE EARTH’S CRUST

  2. What is a mineral? A mineral: • is inorganic • is naturally occurring • is a crystalline solid • has a definite chemical composition to 9.1

  3. Inorganic? • Inorganic means that it is not made by a living organism. • Coal is made from the remains of plants. • Coal is NOT a mineral because it is NOT inorganic. to “What is a Mineral?”

  4. Naturally Occurring? • Steel and brass are compounds made by humans. • Steel and brass are not found in nature • Steel and brass are NOT naturally occurring and so they are NOT minerals. to “What is a Mineral?”

  5. A Crystalline Solid? • A solid is the physical form of matter with a definite shape and volume. • Crystalline means the atoms are arranged in a regular and repeatingpattern:

  6. Definite Chemical Composition? • Calcite consists of calcium, carbon, and oxygen in definite amounts. Calcite is a mineral • Concrete consists of cement, gravel, sand, and water. The amounts of each can vary depending on what you are using the concrete for. Concrete is not a mineral to “What is a Mineral?”

  7. The Two Main Mineral Groups 1. Silicates: Minerals that containsilica (silicon [Si] and oxygen [O] combined), and usually some other element(s). Silicate minerals make up 96% of the earth’s crust. Most common are Feldspars. 2. Nonsilicates: Minerals that do not contain silica. to 9.1 X

  8. Most Common Elements magnesium (Mg) aluminum (Al) silicon (Si) oxygen (O) sodium (Na) potassium (K) calcium (Ca) iron (Fe) to 9.1 X

  9. Six Nonsilicate Groups 1. Carbonates • Contain CO3 (carbonate group) • Examples calcite, dolomite 2. Halides • Contain a halide element (Group VIIA on the Periodic Table) • Examples halite, fluorite 3. Native Elements • Elements uncombined with other elements • Examples sulfur 4. Oxides • Contain oxygen and an element other than silicon • Examples hematite 5. Sulfates • Contain SO4 (sulfate group) • Example gypsum 6. Sulfides • Contain sulfur and another element • Examples galena, pyrite to 9.1

  10. Characteristics of Minerals Color Luster Streak Cleavage/Fracture Hardness Crystal Shape Density to 9.2

  11. quartz feldspar calcite talc calcite quartz Color? Easiest property to see, but seldom useful Many minerals are the same color Some minerals come in several colors

  12. Color? For a few minerals, color is a very good property for identification! Here are some examples: • pyrite • sulfur • galena to “Characteristics”

  13. Luster? • Definition: light reflectedfrom the surface of a mineral • Two main types: 1. metallic—looks like polished metal 2. nonmetallic—does not look like polished metal! to “Characteristics”

  14. Streak? • Definition: color of a mineral in powdered form • Rub the mineral on a piece of unglazed ceramic tile (called a streak plate) • Most metallic minerals have dark streak • Most nonmetallic minerals have white or light-colored streak to “Characteristics”

  15. Cleavage? • Definition: splitting of a mineral along smooth, flat surfaces • Cleavage surfaces form where atomic bonds areweak to “Characteristics”

  16. quartz Fracture? • Definition: breakage along irregular surfaces (absence of cleavage) to “Characteristics”

  17. Hardness? • Definition: ability of a mineral to resist scratching Softest What is the hardness of a mineral that can scratch feldspar but not quartz? 6.5 Hardest to “Characteristics”

  18. amphibole crystals no crystal faces crystal faces on all sides Crystal Shape? • Definition: the form taken by a mineral as a result of its internal arrangement of atoms • Flat surfaces on crystals are called “crystal faces.” • Most crystals don’t show crystal faces because they don’t have enough room to form. to “Characteristics”

  19. Density? • Definition: the amount of matter in a given volume of a substance (formula is: density = mass/volume, or D = m/v) • When you have two objects the same size, the one that “feels heavier” has higher density, the one that “feels lighter” has lower density. • Go to Gizmo to “Characteristics”

  20. Special Properties of Minerals • Magnetism • Fluorescence and phosphorescence • Double refraction • Radioactivity • Reaction to hydrochloric acid to 9.2

  21. Magnetism? • Most common magnetic mineral is: magnet ite • Sometimes magnetic: pyrite (fool’s gold) to Special Props

  22. Fluorescence/Phosphorescence? • Fluorescence glows under ultraviolet light • Phosphorescence glows after ultraviolet light is turned off to Special Props

  23. Double Refraction? • Transparent minerals that can split a light ray into two parts (ex: calcite) to Special Props

  24. processed uranium ore uraninite uranium oxide Radioactivity • The breakdown of a nucleus because it is unstable • Caused by arrangement and number of protons and neutrons in the nucleus to Special Props

  25. Mineral Resources • Steel is made from iron and iron rich minerals (cars, building material) • Quartz (sand) used for making glass • Alloys of magnesium and aluminum • Titanium and molybdenum (aircraft and bicycles) • Gemstones (diamonds for jewelry and cutting and grinding tools) • Graphite (pencils, paint,lubricants and batteries) • Galena (lead) used in car batteries; in solder

  26. Mineral Identification • Mineral Identification Activity

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