Mohs Scale

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Related to Hardness scale: Vickers hardness 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.

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 ?
Moh's hardness scale is a comparative scale for minerals, whereby the softest mineral (talc) is placed at 1 and the hardest mineral (diamond) is placed at 10, with all other minerals ordered in between, according to their hardness.
All sources used in compiling this paper agree that Friedrich Moh (1773-1839), a German mineralogist, invented Moh's hardness scale.
Moh's hardness scale is still being used today by mineralogists and gemmologists, although metallurgists have little use for it now.
The hard phases of the material measure over 1000HV50 on the Vickers hardness scale, while the softer matrix provides for longer tool life when bevel cutting the seats, for example.
Quartz is one of the hardest minerals on Earth -- a seven on the Mohs Hardness Scale (a diamond is 10) -- making Silestone naturally scratch-resistant.
0 mm-anodized aluminum alloy -- Enclosure is built with a hardness scale 3 which guards against scratch, dust and fingerprints -- Power button & LCD display's luminescent backlight always glow in the dark -- LCD display, motor-driven door, and luminescent backlight keep working even when the system is off -- USB 2.
The DigiChamber operates according to the ASTM D2240 and DIN 53505 standards and can be equipped to test for a range of durometer hardness scales.
For example, the Rockwell hardness scales are distinguished by the amount of static force applied (e.
Materials of ASTM hardness scales A through V can be evaluated.
For hardness conversion based on ISO and ASTM standards, the user selects the appropriate material type table and on entering a value, the input can be converted to other hardness scales.
The Mohr or the Knoop hardness scales have been used to compare the hardness of various materials for both materials of construction of the mixer, as well as for the fillers that are being mixed.
They both agreed that there was some correlation between the type A durometer and BS hardness scales.