Hardness Material 1 Talc—easily scratched by the fingernail 2 Gypsum—just scratched by the fingernail 3 Calcite—scratches and is scratched by a copper coin 4 Fluorite—not scratched by a copper coin and does not scratch glass 5 Apatite—just scratches glass and is easily scratched by a knife 6 Orthoclase— easily scratches glass and is just scratched by a file 7 Quartz—not scratched by a file 8 Topaz 9 Corundum 10 DiamondThe scale has been extended as follows:
Hardness Material 1 Liquid 2-6 As indicated above on the chart 7 Vitreous pure silica 8 Quartz 9 Topaz 10 Garnet 11 Fuzed zirconia 12 Fuzed alumina 13 Silicon carbide 14 Boron carbide 15 Diamond (195)