Hardness

The hardness of a mineral indicates how well it resists scratching and abrasion. It is measured on a numerical scale, from 1 (softest) to 10 (hardest):

1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
6. Orthoclase Feldspar
7. Quartz
8. Topaz
9. Corundum
10. Diamond

Chesterman, p. 27

Sources

• Chesterman, Charles W. The Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf: New York (1987)