Mohs Hardness Scale

The Mohs hardness scale is a scratch resistance test that can be applied to various minerals. It was created in 1812 by German geologist Friedrich Mohs and is one of several tests used to document mineral hardness. Minerals are rated on a scale of one through ten with each number correlating to a different mineral type. The mineral that is to be tested is scratched by a mineral from the scale system, and the final result is determined by documenting whether the mineral surface is scratched by a mineral of known hardness. The Mohs hardness scale is considered an arbitrary gauge and is not considered accurate for industrial materials, such as steel or ceramic.

See chart below for the Mohs hardness mineral scale:

Mineral Mohs Hardness Observations
Talc 1 Easily scratched by fingernail
Gypsum 2 Can be scratched by fingernail
Calcite 3 Easily scratched with sharp metal edge
Apatite 5 Can be scratched with sharp metal edge, not easily
Orthoclase 6 Cannot be scratch with sharp metal edge, can scratch glass with difficulty
Quartz 7 Easily scratches glass
Topaz 8 Very easily scratched glass
Corundum 9 Cuts glass
Diamond 10 Used as a glass cutter


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