Mohs scale
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The Mohs scale of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material.
Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale
Talc block
Gypse Arignac
Calcite sample 2
Vickers hardness test
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The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test
A Vickers hardness tester
The pyramidal diamond indenter of a Vickers hardness tester
This is a good indentation.