Developed by Moh, a German mineralogist, this table is not a scale in which the numbers indicate equal divisions of hardness. In other words, the intervals of hardness between the numbers are not equal. Moh's Scale is valuable, when testing the relative hardness of gem material, i.e., a mineral of hardness 8 will scratch another mineral of hardness 7.
|
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 |
|
