Mohs Hardness Scale

A relative scale from 1 (softest) to 10 (hardest).

1
Talc

Softest mineral, can be scratched with fingernail

2
Gypsum

Fingernail (2.5) can barely scratch

3
Calcite

Copper coin can scratch

4
Fluorite

Easily scratched with knife

5
Apatite

Knife can barely scratch

6
Orthoclase

Can scratch glass

7
Quartz

Scratches glass easily

8
Topaz

Scratches quartz

9
Corundum

Scratches topaz, second hardest

10
Diamond

Hardest natural material