AIGS Hardness Table
Hardness is the power a mineral has to resist scratching (abrasion)
In 1812 the Mohs scale of mineral hardness was devised by the German mineralogist Frederich Mohs (1773-1839),
who selected the ten minerals because they were common or readily available. The
scale is not a linear scale, but somewhat arbitrary.
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 in fluorite prevents tooth decay.
|
|
5
|
Apatite
|
When you are hungry you have a big "appetite".
|
|
6
|
Orthoclase
|
Orthoclase is a feldspar, and in German, "feld" means "field".
|
|
7
|
Quartz
|
|
|
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.
|
Hardness of some other items:
|
2.5
|
Fingernail
|
|
2.5–3
|
Gold, Silver
|
|
3
|
Copper penny
|
|
4-4.5
|
Platinum
|
|
4-5
|
Iron
|
|
5.5
|
Knife blade
|
|
6-7
|
Glass
|
|
6.5
|
Iron pyrite
|
|
7+
|
Hardened steel file
|