Christina Parker Photography

"Preserving Time for Generations to Come"

Moh’s Scale of mineral hardness January 29, 2009

Filed under: Facts — precioussadies @ 10:21 pm
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I usually refer to the Moh’s scale of mineral hardness  in my descriptions of  jewelry pieces.

Friedrich Mohs’ a German mineralogist, created this scale in 1812.   This scale helps determine how soft or hard a gemstone is.   The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, and/or the softest material that can scratch the given material.    He based the scale on 10 readily available minerals.

To help you understand, on the Mohs scale, a pencil “lead” or graphite has a hardness of 1; A fingernail  2.5; a copper penny, about 3.5; a knife blade, 5.5; window glass, 5.5; and a steel file, 6.5.

Hardness Substance or Mineral
1 Talc, Graphite
2.5 to 3 Pure gold, silver, aluminum
3 Calciate, Copper
4 Fluorite
4 to 4.5 Planitum
4 to 5 Iron
5 Apatite
6 Orthoclase
6 Titanium
6.5 Iron Pyrite
6 to 7 Glass, Fuzed quartz
7 Quartz
7 to 7.5 Garnet
7 to 8 Hardened Steel
7.5 Tungsten
8 Topaz
8.5 Chrysoberyl, chromium
8.5 to 9 Tungsten Carbide
9 Cordunum
9 to 9.5 Carborundum
<10 Ultra-hard fullerite
10 Diamond

Diamond is the hardest.  To cut diamond, you actually cut it against diamond.

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