Measuring the hardness of ERIC
Measuring the hardness of minerals The visible difference on the graph between minerals 9 (corundum) and 10 (diamond) is far greater than that of 1 (talc) and 2 (gypsum). This means the table does not indicate scale, and is really more an ordered list of minerals' hardness. How does it work? Steps for testing the hardness of a mineral: 1.