"MOH'S SCALE"

"Minerals A to Z"

A-

B-

C-

D-

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F-

G-

H-

I-

J-

K-

L-

M-

N-

O-

P-

Q-

R-

S-

T-

U-

V-

W-

X-

Y-

Z

MOH'S SCALE:

HARDNESS MINERAL ASSOCIATIONS AND USES
1 Talc Talcum powder.
2 Gypsum Plaster of paris. Gypsum is formed when seawater evaporates from the Earth’s surface.
3 Calcite Limestone and most shells contain calcite.
4 Fluorite Fluorine from fluorite prevents tooth decay.
5 Apatite Apatite is a mineral in vertebrate bones and teeth.
6 Orthoclase Orthoclase is a feldspar, and in German, "feld" means "field".
7 Quartz Quartz is the most common mineral in the Earth's crust.
8 Topaz The November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8.
9 Corundum Sapphire and ruby are varieties of corundum. Twice as hard as topaz.
10 Diamond Used in jewelry and cutting tools. Four times as hard as corundum.

One of the most important tests for identifying mineral specimens is the Mohs Hardness Test. This test compares the resistance of a mineral to being scratched by ten reference minerals known as the Mohs Hardness Scale (see Table 1). The test is useful because most specimens of a given mineral are very close to the same hardness. This makes hardness a reliable diagnostic property for most minerals.

Friedrich Mohs, a German mineralogist, developed the scale in 1812. He selected ten minerals of distinctly different hardness that ranged from a very soft mineral (talc) to a very hard mineral (diamond). With the exception of diamond, the minerals are all relatively common and easy or inexpensive to obtain.