The Mohs Scale

The Mohs scale was developed in 1812 by Friedrich Mohs. It has become a valuable aid to identifying minerals ever since. Here are the ten standard minerals in the Mohs scale.

1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
6. Feldspar
7. Quartz
8. Topaz
9. Corundum
10. Diamond
    

You use the Mohs scale by testing your unknown mineral against one of these standard minerals. Whichever one scratches the other is harder, and if both scratch each other they are both the same hardness.

There are a few common objects that also fit in the Mohs scale. A fingernail is 2½, a penny is just under 3, a knife blade is 5½, glass is 5½, and a good steel file is 6½.

Hope this helps you with your gemstone identification.