Mohs hardness scale Standards

MOHS hardness scale

Scratch-resistance measurement glass


Scratch Hardness Testing

The Mohs hardness is a way to measure the scratch resistance of a material.

This scale was developed in 1812 by German geologist and mineralogist Friedrich Mohs (1773-1839).

The idea behind the Mohs hardness scale is quite simple.

The Harder material scratches the softer material.

The Mohs hardness scale is based on a scale of 1 to 10, with diamond being the hardest material with a top value of 10. Materials are tested against each other, and if one scratched the other, it would give the material a higher value.

For example, gypsum can scratch talc; therefore, it has a higher Mohs value than talc.

The Mohs hardness scale is easy to use, but it lacks accuracy because of only 10 scales, a near logarithmic relationship to absolute hardness. A difference of Mohs Hardness of 5 and 6 cannot be truly determined and is more of an approximation than the more sophisticated and high precision hardness measuring methods like Vickers or Rockwell.

The advantage of the Mohs hardness measuring method is the scratching process compared to the denting of the other two methods. This is especially useful for crystalline materials like glass or ceramics that will shatter and not deform.

Mohs hardness scale

Hardness Material
1 Talcum powder
2 Rock salt
3 Calcite
4 Fluorspar
5 Apatite
6 Feldspar
6,5 Borosilicate glass
7 Quartz
8 Topaz
9 Corundum, sapphire, ruby
10 Diamond