Mineral Identification

Pyrite

Metallic Luster. 6.5-6.0 hardness. Greenish-black streak. 5 specific gravity. Brass yellow/brown, brittle, no cleavage, cubic crystals. "Fools gold"

Magnetite

Metallic Luster. 6.0 harness. Dark grey streak. 5.2 specific gravity. Dark grey to black, no obvious cleavage. MAGNETIC!!

Hematite

Metallic Luster. 6.5-5.0 hardness. Red-Brown streak. 5.3 specific gravity. Silver-grey color, may have tiny glittery flakes, may tarnish red.

Goethite

Metallic Luster. 6.5-5.0 hardness. Yellow-Brown streak. 4.4 specific density. Yellow-brown to black color, in radiating masses.

Garnet

Non Metallic Luster. 7.0 hardness. No streak. 4 S.G. Dark red brown to pink, yellow green or black coloring. No cleavage but may show parting; transparent to translucent; commonly forms dodecahedra.

Olivine

Non Metallic Luster. 7.0 hardness. No streak. 3.2-3.5 SG. Yellow to green color. No cleavage, conchoidal fracture, often granular masses.

Quartz

Non Metallic Luster. 7.0 hardness. No streak. 2.7 SG. Colorless to light dark colors, transparent to translucent, greasy luster, no cleavage, conchoidal fracture, may form hexagonal prisms.

Potassium Feldspar

Non Metallic Luster. 6.0 hardness. White streak. 2.6 SG. White, pink/orange, green colors, too cleavages at ~90. may show subparallel exsolution lamellae.

Plagioclase Feldspar

Non Metallic Luster. 6.0 harness. White streak. 2.7 SG. White to dark grey color, striations on some cleavage planes; two cleavage planes at ~90, rare blue iridescence.

Augite (Pyroxene)

Non Metallic Luster. 6.0-5.5 harness. White to pale green streak. 3.2-3.4 SG. Green to black color, dull, stout crystals; two cleavage directions that intersect at ~87 and 93.

Hornblende (Amphibole)

Non Metallic Luster. 5.5 hardness. White to pale green streak. 3.3 SG. Green to black color, opaque, two cleavage directions at 56 and 124. Slender crystals, may be splintery.

Hematite

Non Metallic Luster. 5.5 hardness. Red-brown streak. 5.2 SG. Red to brown color, massive, opaque, earthy luster.

Goethite ("Limonite")

Non Metallic Luster. 5.5 hardness. Yellow-brown streak. 3.6-4.4 SG. Yellow-brown to dark brown color, amorphous, but may be pseudomorphic after pyrite

Dolomite

Non Metallic Luster. 3.5 harness. White streak. 2.9 SG. White, grey, pink or brown color, rhombohedral cleavage; subdued effervescence in dilute HCl

Calcite

Non Metallic Luster. 3.0 hardness. White streak. 2.7 SG. Colorless- white color, transparent to translucent, rhombohedral cleavage, REACTION WITH HCl

Biotite

Non Metallic Luster. 3-2.5 hardness. Grey-brown streak. 2.8-3 SG. Dark brown to black coloring, one perfect cleavage, elastic thin sheets. Mica family

Halite

Non Metallic Luster. 2.5 hardness. White streak. 2.2 SG. Colorless, white, yellow, red, blue, brown color. Cubic crystals and cubic cleavage, SALTY TASTE.

Muscovite

Non Metallic Luster. 2.5-2.0 harness. White streak. 2.7-2.8 SG. Colorless, grey, yellow, brownish color. One perfect cleavage; elastic thin sheets. Mica family

Gypsum

Non Metallic Luster. 2.0 hardness. White streak. 2.3 SG. Colorless, white, may be colored orange by iron oxide; non-greasy feel, colorless sheets, fibrous-silky masses, or massive.

Chlorite

Non Metallic Luster. 2.0 hardness. White streak. 2.6-3.0 SG. Dark green, one perfect cleavage, flexible.

Kaolinite

Non Metallic Luster. 2.0-1.0 harness. White streak. 2.6 SG. White to very light brown color, one perfect cleavage (usually not visible), earthy microcrystalline masses. Powdery

Talc

Non Metallic Luster. 1.0 hardness. White streak. White, yellow, grey, green, pink, brown color. Soapy feel, massive or foliated, waxy to silky to pearly luster.

mineral properties (8)

luster
hardness
streak
crystal form
cleavage and fracture
specific gravity
magnetism
effervescence

Mineral Qualifications

-Solid at surface temperature and pressure
-Naturally occuring
-Inorganic, no C=C bonds (double carbon bonds)
-ordered internal structure
-Definite chemical composition

Luster

the way light reflect off of mineral
Metallic
nonmetallic pearly/waxy
nonmetallic dull/earthy
nonmetallic vitreous/glassy

hardness

a minerals resistance to being scratched

comparison items, in order of hardness-

fingernails
penny
window glass
knife blade, masonry nail
unglazed porcelain tile
steel file

streak

color of a mineral powder determined by rubbing sample on streak plate

crystal form

how the crystals form...
large?
small?
close together?

cleavage, definition

the tendency for minerals to break along flat planes of weakness in their atomic structure

cleavage planes (5)

basal
prismatic at 90
prismatic not at 90
cubic
rhombohedral

basal

1 plane of cleavage

prismatic at 90

2 planes of cleavage meet at 90 degrees angles

prismatic not at 90

2 planes of cleavage meet at not 90 degree angles

cubic

3 planes meet at abt 90 degree angles

rhombohedral

3 planes meet at non 90 degree angles

fracture

when minerals break with no smooth flat planes at all

conchoidal

type of fracture that breaks with a curved surface like glass

irregular

type of fracture that breaks with no discernible pattern at all

specific gravity

density of mineral

magnetism

is mineral magnetic?

effervescence

does a mineral react to hydrochloric acid? if it bubbles, it does!

effervescences vigorously

super bubbly effervescence

limited effervescence

when you can hear a reaction, but not see one

The order of Mohs' hardness scale, from 1 to 10 (mnemonic)

True Geologists Climb Faults And Observe Quarries To Contemplate Deformation

Talc, Gypsum, Calcite, Fluorite, Apatite, Orthoclase feldspar, Quartz, Topaz, Corundum, Diamond

The order of the oldest geologic era to the most recent.

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Precambrian, Paleozoic, Mesozoic, Cenozoic