| 1 | Talc | Easily scratched by a fingernail; soft and greasy to the touch. |
| 2 | Gypsum | Can be scratched by a fingernail (~2.5). |
| 3 | Calcite | Scratched by a copper coin; about the hardness of a fingernail's limit. |
| 4 | Fluorite | Scratched easily by a knife or steel nail. |
| 5 | Apatite | Just barely scratched by a knife; close to a steel blade (~5.5). |
| 6 | Orthoclase | Scratches glass; scratched by a steel file or hardened steel. |
| 7 | Quartz | Scratches glass and steel; hardness of a typical streak plate. |
| 8 | Topaz | Scratches quartz; harder than most common materials. |
| 9 | Corundum | Scratches topaz; includes ruby and sapphire varieties. |
| 10 | Diamond | Hardest natural material; scratches all others. |