Mohs' scale of mineral hardness
Ranking
Mineral
Natural form
Form of usage
Softest
1
Talc
2
Gypsum
3
Calcite
4
Fluorite
5
Apatite
6
Feldspar
7
Quartz
8
Topaz
9
Corundum
Hardest
10
Diamond
Diagrams | Earthguide