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Mohs scale of hardness

There are several ways to tell minerals apart from each other. An obvious one is colour, or shape of crystal. However, one very useful property is hardness.

In 1812, Mohs arranged ten minerals in order of hardness, so each will scratch those lower in the scale. This is still used today. It is not a regular scale. There is a far greater gap between diamond and corundum, than between any other two. But it is a useful way to measure the property of hardness. I have not given the Mohr hardness of any minerals (except on this page), but you can find them in any serious book on minerals.

1	2	3	4	5	6	7	8	9	10
Talc	Gypsum	Calcite	Fluorite	Apatite	Moonstone	Quartz	Topaz	Corundum	Diamond
Scratched by finger nail		Scratched by steel knife			Will scratch glass - gemstones