CGminrls
MINERAL IDENTIFICATION
Define mineral:
1. Naturally occurring
2. inorganic *(mineraloid)
3. definite crystalline shape (crystal classes)
4. well defined chemical composition (within limits)
5. Distinct physical properties
Physical Properties
I. Luster
Metallic
or
silvery (Galena #5)
brassy
golden
Non-metallic
glassy
pearly
soapy
adamintine
earthy
*magnet test--Magnetite #2
II. Streak
a. red brown (Hematite #3)
b. yellow brown (Limonite #4 or Goethite)
c. black--grey black (Pyrite #7 or Chalcopyrite #8)
III. Hardness
Two Girls Came From Africa Feeling Quite Tipsy Carrying Diamonds
1 Talc (#27)
2 Gypsum (#12)
(Fingernail 2.5)
3 Calcite (#11)
4 Fluorite (#14)
5 Apatite
(knife or nail)
(Glass Plate 5.5)
6 Feldspar (#16, #17)
7 Quartz (18)
8 Topaz
9 Corundum-sapphire, ruby
10 Diamond
Feldspar (60% of crust of earth)
1. Plagioclase (17)
2. Orthoclase (16)
striations or record grooves
CGminrls
discontinuous wavy lines
IV. Cleavage-Tendency of a mineral to break along planes of weakness (look for sets of parallel
lines)
1. one direction--basal
e.g. muscouite #20
biotite #21
2. two directions
a. at right angles (prismatic) Feldspars
b. not at right angles
Feldspars
Hornblende #25
3. Three directions
a. all at right angles
cubic
e.g. halite (#13)
galena (#5)
b. Rhombohedral
e.g. Calcite (#11) fizzes in HCL
4. Four way=Octohedral (fluorite #14)
5. 6 way=dodecahedral
sphalerite (#1)
6. Fracture
random breaks
Quartz- concoidal fracture
CGminrls
V.
Specific Gravity
Specific gravity = Weight in air / weight in air - weight in water
VI.
Taste
VII. Acid test (HCl)
VIII. Diaphaneity (ability to transmit light)
Transparent, Translucent, opaque
IX.
Tenacity
Brittle, malleable, ductile,