Minerals, Rocks, and Mineral Resources 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---