earth materials minerals, rocks, and mineral resources
Post on 03-Jan-2016
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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---
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