A scale for measuring the hardness of a specimen of mineral or other hard substance, prepared in 1812 by Austrian mineralogist Friedrich Mohs, being a series of ten specified minerals in the order of their relative hardness - the intervals between the listed minerals not being equal or proportionate - against which the specimen is rated. The minerals on the scale are:
talc -1
gypsum -2
calcite -3
fluorspar -4
apatite -5
orthoclase -6 (feldspar)
quartz -7
topaz -8
sapphire (corundum -9
diamond -10