Mohs Scale

The Mohs Scale of Mineral Hardness defines the resistance to scratching of one mineral to another. The scale was derived by the German mineralogist Friedrich Mohs in 1812, and is the most commonly recognized hardness scale used in science. The scale is not purely linear, but ranges from 1 to 10 depending on the relative hardness of the material in question.

Hardness	Mineral	Absolute Hardness
1	Talc (Mg3Si4O10(OH)2)	1
2	Gypsum (CaSO4·2H2O)	2
3	Calcite (CaCO3)	9
4	Fluorite (CaF2)	21
5	Apatite (Ca5(PO4)3(OH-,Cl-,F-))	48
6	Orthoclase Feldspar (KAlSi3O8)	72
7	Quartz (SiO2)	100
8	Topaz (Al2SiO4(OH-,F-)2)	200
9	Corundum (Al2O3)	400
10	Diamond (C)	1500