Relative and Absolute Hardness scale

Scratch hardness Mohs

Mineral used for comparison

Simple hardness tester

Cutting resistance

(Rosiwal)

1

Talc

Can be scratched with fingernail

0.03

2

Gypsum

Can be scratched with fingernail

1.25

3

Calcite

Can be scratched with copper coin

4.5

4

Fluorite

Easily scratched with knife

5.0

5

Apatite

Can be scratched with knife

6.5

6

Orthoclase

Can be scratched with steel file

37

7

Quartz

120

8

Topaz

175

9

Corundum

1000

10

Diamond

140,000