Mohs Scale(redirected from hardness index)
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Mohs scale[′mōz ‚skāl]
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|
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.