Mohs Hardness Scale
The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material.
The table below shows the hardness for various gemstones.
| Rating | Test Rock | Other Tests |
|---|---|---|
| 1 | Talc | Can be scratched by fingernail |
| 2 | Gypsum | Scratched by copper/bronze coin |
| 3 | Calcite | Scratched by copper/bronze coin |
| 4 | Fluorite | Scratched by steel; scratches coin |
| 5 | Apatite | Scratched by steel; scratches coin |
| 6 | Feldspar | Scratches glass |
| 7 | Quartz | Not scratched by steel |
| 8 | Topaz | Not scratched by steel |
| 9 | Corundum | Not scratched by steel |
| 10 | Diamond | No mineral harder |
The table below shows the hardness for various gemstones.
| Gemstone | Hardness |
|---|---|
| Serpentine | 1.5 |
| Amber | 2-2.5 |
| Chrysocolla | 2-2.5 |
| Tortoise shell | 2.5 |
| Pearl | 2.5-3.5 |
| Jet | 2.5-4 |
| Coral | 3.5 |
| Rhodochrosite | 3.5-4.5 |
| Rock crystal | 3.5-5 |
| Lapis Lazuli | 5.5 |
| Moonstone | 5.5-6 |
| Turquoise | 5.5-6 |
| Opal | 5.5-6.5 |
| Tanzanite | 6 |
| Chalcedony | 6.5-7 |
| Jade | 6.5-7 |
| Peridot | 6.5-7 |
| Garnet | 6.5-7.5 |
| Kunzite | 7 |
| Quartz | 7 |
| Tourmaline | 7-7.5 |
| Zircon | 7.5 |
| Beryl | 7.5-8 |
| Spinel | 8 |
| Topaz | 8 |
| Chrysoberyl | 8.5 |
| Sapphire | 9 |
| Ruby | 9 |
| Diamond | 10 |
Source: Wikipedia, Dragon #248
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