Mohs hardness scale
Escala de dureza de Mohs
- Date
- 1812 · confidence high
- Place
- Graz, Styria, Austria
- Credited to
- Friedrich Mohs
- Field
- Knowledge & symbols
What it is
An ordinal scale of ten reference minerals, from talc (1) to diamond (10), in which each scratches the previous ones. It allows the hardness of minerals to be compared with a scratch test in the field, without instruments.
The scale is ordinal: it does not measure regular intervals (diamond, 10, is about four times harder than corundum, 9, which barely exceeds topaz, 8). Mohs presented it in 1812 and detailed it in 1822.
What it led to
- identification of minerals and gems in the field
- quantitative hardness tests (Brinell, Vickers, Knoop)
- classification of materials for abrasives and tools