Hardness Test - Mohs hardness

Principle

 

In the empirically arranged hardness scale each material can be scratched with the consecutive one.

Mohs hardness	Mineral	Formulas
1	Talc	Mg3(Si2O5)2(OH)2
2	Gypsum	CaSO4 x 2H2O
3	Calcite	CaCO3
4	Fluorite	CaF2
5	Apatite	Ca5(PO4)3(F, Cl)
6	Orthoclase feldspat	K AlSi3O5
7	Quartz	SiO2
8	Topas	Al2SiO4(F, OH)
9	Corundum	Al2O3
10	Diamond	C

History

 

This hardness scale, developed by Mohs in 1882, was the first quantitative evaluation of material hardness which was of great importance.
However, it became obvious that hardness tests according to Mohs did not meet the requirements of material producing or -processing manufacturing enterprises.
Nowadays, Mohs hardness scale finds its application only in mineralogy for classification purposes.

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