Mohs Scale of Mineral Hardness

Mohs' scale of mineral hardness characterises the scratch resistance of various minerals through the ability of a harder material to scratch a softer. It was created by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science.

Mohs based the scale on ten readily available minerals. Materials are characterised against the scale by finding the hardest material that they can scratch.

The table below shows comparison with absolute hardness measures by a sclerometer. Mohs' is a purely ordinal scale with, for example, corundum being twice as hard as topaz , but diamond , almost four times as hard as corundum.

Hardness Mineral Absolute Hardness

1	Talc	1
2	Gypsum	3
3	Calcite	9
4	Flourite	21
5	Apatite	48
6	Orthoclase Feldspar	72
7	Quartz	100
8	Topaz	200
9	Corumdum	400
10	Diamond	1500