Mohs Scale


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Mohs scale

[′mōz ‚skāl]
(mineralogy)
An empirical scale consisting of 10 minerals with reference to which the hardness of all other minerals is measured; it includes, from softest (designated 1) to hardest (10): talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond.

Mohs’ Scale

 

a ten-point scale for measuring the relative hardness of minerals. Proposed by the German scientist F. Mohs in 1811, the scale (see Table 1) comprises ten standards of hardness.

Table 1. Mohs’ scale of hardness
1Talc6Orthoclase
2Gypsum7Quartz
3Calcite8Topaz
4Fluorite9Corundum
5Apatite10Diamond

The relative hardness is determined by scratching the surface of the test specimen with a standard of the Mohs’ scale. If, for example, the standard apatite, having a hardness of 5, scratches the specimen and the specimen itself leaves a mark on the surface of fluorite, the standard with a hardness of 4, then the hardness of the mineral being tested is approximately 4.5. Mohs’ scale facilitates the rapid identification of minerals.

References in periodicals archive ?
Dispute: The Mohs scale ranks the hardness of minerals--from 1 for softest to 10 for hardest The diamond rates a 10 because it is the hardest mineral on Earth.
Due to its hardness (diamond is 10 on the Mohs scale, moissanite 9.
As one of the hardest materials used in the manufacture of rings, Tungsten Carbide is also the most scratch-resistant metal on the jewelry ring market, ranking behind a diamond on the Mohs scale of mineral hardness.