Minerals

Naturally Occurring
Inorganic
Crystalline
Solid
Just remember NICS!

Mineral Properties

LUSTER
- how a mineral “looks” in reflected light
TYPES OF LUSTER

Metallic
Non-Metallic
Glassy
Earthy
Pearly
Resinous

STREAK
- the color of the mineral in powder form
if the mineral is harded than the plate, there is no streak. If softer, then note the color.

**NOTE ABOUT COLOR**

Color is never to be used for identification by itself!!! Many minerals show similiar colors, or may show many different colors!

HARDNESS
- the hardness of a mineral relative to other minerals
MOHS HARDNESS SCALE
- Scale from 1 to 10, 1 (Talc) is softest, 10 (Diamond) is hardest.
1 Talc
2 Gypsum
3 Calcite
4 Fluorite
5 Apatite
6 Feldspar
7 Quartz
8 Topaz
9 Corundum
10 Diamond

Fingernail ~ 2.2
Penny ~ 3.5
Nail ~ 5
Glass plate ~ 5.5

CLEAVAGE

- the ordered way a mineral breaks due to its crystal nature
- cleavage “planes” are parralel zones in rock which due to weaker chemical bonds are 2D planes alond which the mineral tends to break.
- a mineral can have 0,1,2,3,6 cleavage planes or no cleavage at all.
- look for parallel surfaces, incipient cracks, planes of weakness

FRACTURE
- lack of cleavage. minerals break along random surfaces with no pattern

TYPES OF FRACTURE
Chonchoidial Fracture
- “clam-shell” fracture, has a scalloped look. i e Quartz.
Random Fracture - self-explanatory


HABIT
- the common way a crystal grows
Examples: Quartz, Garnet

Types of Habit
Fibrous
Massive
Tabular

OTHER CHARACTERISTICS

- Taste (Halite is salty)
- Feel (Talc is soapy)
- Odor (Kaolinite smells like wet clay)
- Reaction to HCL acid (Calcite fizzes in acid)
- Heft (Barite is dense and heavy)