RELATIVE HARDNESS INFORMATION

MOHS SCALE of the RELATIVE HARDNESS OF MINERALS

 

Mohs’ scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created, in 1812, by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science.

Mohs based the scale on ten minerals that are all readily available except the first one, diamond. 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. For example, if some material is scratched by apatite but not by fluorite, its hardness on Mohs scale is 4.5.

The table below shows comparison with absolute hardness measures by a sclerometer. Mohs’ is a purely ordinal scale with, for example, corundum being twice as hard as topaz, but diamond, almost four times as hard as corundum.

MOHS SCALE

10 DIAMOND

9 Corundum (RUBY, SAPPHIRE)

8 Topaz

7.5 Beryl (EMERALD, Aquamarine)

6.5-7.5 Garnet

7 Quartz (Amethyst, Citrine, Agate)

6.5 Steel File

6 Feldspar (Spectrolite)

5.5-6.5 Most Glass

5 Apatite

4 - 4.5 PLATINUM-Pure

4 Fluorite

3 Calcite (Also a penny!)

2.5 GOLD-Pure(24Carat), SILVER-Pure,(Fingernail)

2 Gypsum

1 Talc

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