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---