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Our Glaciers: Then and Now activity kit helps you see the changes taking place in glaciers around the world. See all our activity kits and classroom activities.

Mohs Hardness Scale

Mohs hardness is measured on a scale from 1 to 10. The scale was made about 200 years ago by Friedrich Mohs. Softer minerals have low numbers and harder 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
Copper penny: 3
Glass: 5.5

To figure out the hardness of a mineral, try to scratch it with an object of known hardness. For instance, if a fingernail cannot scratch a mystery mineral, we know it has a hardness of more than 2.5. If the mystery mineral can't scratch glass, we know it has a hardness of less than 5.5.

Last modified May 1, 2003 by Lisa Gardiner.

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The Fall 2010 issue of The Earth Scientist, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!

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