Minerals, Metals, and Other Materials

Rocks and Minerals

What is the Mohs scale?

The Mohs scale is a standard of ten minerals by which the hardness of a mineral is rated. It was introduced in 1812 by the German mineralogist Friedrich Mohs (1773–1839). The minerals are arranged from softest to hardest. Harder minerals, with higher numbers, can scratch those with a lower number.

The Mohs Scale
Hardness Mineral Comment
1 Talc Hardness 1–2 can be scratched by a fingernail
2 Gypsum Hardness 2–3 can be scratched by a copper coin
3 Calcite Hardness 3–6 can be scratched by a steel pocket knife
4 Fluorite
5 Apatite
6 Orthoclase Hardness 6–7 will not scratch glass
7 Quartz
8 Topaz Hardness 8–10 will scratch glass
9 Corundum
10 Diamond


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