Mohs Hardness Scale
1–10 Mohs hardness reference for minerals.
| # | Mineral | Reference test | Notes |
|---|---|---|---|
| 1 | Talc | Easily scratched by fingernail | Softest known mineral |
| 2 | Gypsum | Scratched by fingernail (~2.5) | Used in drywall |
| 3 | Calcite | Scratched by copper coin (~3) | Limestone, marble |
| 4 | Fluorite | Easily scratched by knife | Fluorescent |
| 5 | Apatite | Scratched by knife (~5.5) | Tooth enamel |
| 6 | Orthoclase | Scratched by steel file (~6.5) | Feldspar |
| 7 | Quartz | Scratches glass | SiO₂, common in granite |
| 8 | Topaz | Scratches quartz | Gemstone |
| 9 | Corundum | Scratches topaz | Sapphire, ruby |
| 10 | Diamond | Hardest natural material | Pure carbon |
About this tool
The 1–10 Mohs scale of mineral hardness from talc to diamond, with reference scratch tools at each step.