Hardness Test - Mohs hardness

Principle

 

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

Mohs hardnessMineralFormulas
 1TalcMg3(Si2O5)2(OH)2
 2GypsumCaSO4 x 2H2O
 3CalciteCaCO3
 4FluoriteCaF2
 5ApatiteCa5(PO4)3(F, Cl)
 6Orthoclase feldspatK AlSi3O5
 7QuartzSiO2
 8TopasAl2SiO4(F, OH)
 9CorundumAl2O3
10DiamondC


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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