Mohs Scale

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.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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
1	Talc	6	Orthoclase
2	Gypsum	7	Quartz
3	Calcite	8	Topaz
4	Fluorite	9	Corundum
5	Apatite	10	Diamond

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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.