Moh’s Hardness Scale

Moh’s Hardness Scale

Compliance Standards

EN – 101, IS 13030, ISO 10545-13, ISO 10545-14, ASTM-97

Applications

  • The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material.

Details

  • The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (1099) is almost four times as hard as corundum. The table below shows comparison with absolute hardness measured by a sclerometer. SUPPLIED WITHOUT DIAMNOND.

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Technical Specifications

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

On the Mohs scale, a pencil lead has a hardness of 1; a fingernail has hardness 2.5; a copper penny, about 3.5; a knife blade, 5.5; window glass, 5.5; steel file, 6.5.[1] Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale.