Mohs Hardness Scale

The Mohs Hardness Scale was devised by Friedrich Mohs in 1812 and is used to identify minerals. There are ten standard minerals in the scale, talc being the softest and diamond being the hardest.

To use the scale, a mineral is tested against one of the standard minerals listed below. Whichever one scratches the other is harder.

The Mohs scale is strictly a relative scale. In terms of absolute hardness, diamond actually is 4 times harder than corundum, and 6 times harder than topaz. By using sensitive equipment, a comparison can be made to determine the absolute hardness. The results are shown in the chart below.

 

Mohs Hardness Scale
Mineral Relative Ranking Absolute Ranking
Talc 1 1
Gypsum 2 2
Calcite 3 9
Fluorite 4 21
Apatite 5 48
Feldspar 6 72
Quarts 7 100
Topaz 8 200
Corundum 9 400
Diamond 10 1600