The Mohs scale is a standard of ten minerals by which the hardness of a mineral is rated. It was introduced in 1812 by the German mineralogist Friedrich Mohs (1773–1839). The minerals are arranged from softest to hardest. Harder minerals, with higher numbers, can scratch those with a lower number.
| The Mohs Scale |
| Hardness |
Mineral |
Comment |
| 1 |
Talc |
Hardness 1–2 can be scratched by a fingernail |
| 2 |
Gypsum |
Hardness 2–3 can be scratched by a copper coin |
| 3 |
Calcite |
Hardness 3–6 can be scratched by a steel pocket knife |
| 4 |
Fluorite |
|
| 5 |
Apatite |
|
| 6 |
Orthoclase |
Hardness 6–7 will not scratch glass |
| 7 |
Quartz |
|
| 8 |
Topaz |
Hardness 8–10 will scratch glass |
| 9 |
Corundum |
|
| 10 |
Diamond |
|
