Mohs Hardness Scale

Mohs Hardness Scale
Mohs Hardness Scale

National Park Service

The Mohs Hardness Scale is used as a convenient way to help identify minerals. A mineral's hardness is a measure of its relative resistance to scratching, measured by scratching the mineral against another substance of known hardness on the Mohs Hardness Scale. This graphic outlines the index minerals and some common objects that are used to determine a mineral's hardness.

This method is especially useful for identifying minerals in the field because you can test minerals against some very common objects (fingernail, a penny, a nail). The scale is named for its creator, the German geologist and mineralogist Friedrich Mohs. However, the method of comparing hardness has been used as far back as 300 BC, as mentioned by Theophrastus in his treatis On Stones.

Related Links

NPS—Geoscience Concepts
NPS—Geology

Last updated: February 6, 2018