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EARTH MATERIALS. Minerals, Rocks, and Mineral Resources. MINERALS. Naturally occurring Inorganic Crystalline solid Definite chemical composition. ARE THESE MINERALS? WHY OR WHY NOT?. Diamond Coal Wood Quartz Graphite. WHAT IS CRYSTALLINE?.
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EARTH MATERIALS Minerals, Rocks, and Mineral Resources
MINERALS • Naturally occurring • Inorganic • Crystalline solid • Definite chemical composition
ARE THESE MINERALS? WHY OR WHY NOT? • Diamond • Coal • Wood • Quartz • Graphite
WHAT IS CRYSTALLINE? • The atoms have a specific arrangement called the crystal structure • Every mineral has its own distinctive crystal structure
CRYSTAL STRUCTURE • The ordered pattern of atoms in the mineral. • Hexagonal • Cubic • Horizontal (thin, flexible sheets)
MINERAL FORMATION • Atoms organize to form crystalline solids • Recrystallization of atoms from solids and liquids in rock-forming environments
MINERAL IDENTIFICATION • The arrangement and type of atoms gives every mineral a set of physical and chemical properties that can be used to identify the mineral.
1. COLOR • Many minerals have a characteristic color • Some colors may be caused by impurities • Many minerals come in more than 1 color (variable color).
2. LUSTER • The way a mineral looks in reflected light • Metallic—shines like a metal • Nonmetallic—may be shiny, but does not shine like a metal • Glassy, waxy, pearly, earthy (dull)
3. STREAK • The color of the powdered form of the mineral • Test performed using an unglazed, porcelain streak plate • The streak color is not always the same color as the mineral
4. HARDNESS • Moh’s Scale of Hardness • To test for hardness, scratch the unknown mineral with an object of known hardness. • Objects include glass plate, penny, fingernail.
MOH’S SCALE OF HARDNESS • Ranges from 1 to 10. • 1 is the softest, 10 is the hardest.
1. Talc • 2. Gypsum 2.5 Fingernail • 3. Calcite 3.5 Copper Penny • 4. Fluorite 4.5 Iron Nail • 5. Apatite 5.5 Glass Plate • 6. Feldspar • 7. Quartz 7.5 Streak Plate • 8. Topaz • 9. Corundum • 10. Diamond
FRACTURE • A mineral breaks producing an uneven breaking surface. • Does NOT follow the atomic arrangement. • Irregular, Fibrous, Curved (conchoidal)
CLEAVAGE • The ability of a mineral to break along zones of weakness. • Forms smooth to semi-smooth parallel sides or surfaces. • The break will follow the atomic arrangement. Predictable pattern!
DENSITY • Every mineral has its own specific density. • May be called specific gravity—density compared to water.
OTHER PROPERTIES • Chemical reaction with HCl—Hydrochloric Acid • Acid reacts with the mineral calcite • Magnetism---