Mohs Hardness Scale

A man named Friedrich Mohs knew that different minerals have different hardness! Soft minerals have low numbers. Hard minerals have high numbers.

Mohs scale number (mineral example)
1 (Talc)
2 (Gypsum)
3 (Calcite)
4 (Fluorite)
5 (Apatite)
6 (Orthoclase Feldspar)
7 (Quartz)
8 (Topaz)
9 (Corundum)
10 (Diamond)

Hardness of other common objects
Fingernail: 2.5
Penny: 3
Glass: 5.5

You can figure out the hardness of a mineral! Try to scratch it with your fingernail. If your fingernail cannot scratch the mineral, you know it has a hardness of more than 2.5. If the mineral can't scratch glass, you know it has a hardness of less than 5.5.

Last modified May 1, 2003 by Lisa Gardiner.

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