A relative scale of hardness, based on the ability of a harder mineral to scratch a soft one. The ten minerals in the scale are: talc, gypsum, calcite, fluorite, apatite, feldspar, quartz, topaz, carborundum, and diamond. Use Moh’s scale by testing an unknown mineral against one of these standard minerals. Whichever one scratches the other is harder, and if both scratch each other they are both of the same hardness.