Granite is a 6 to 7 on the Mohs hardness scale. The Mohs hardness scale was developed by the German mineralogist Friedrich Mohs to determine the hardness of a mineral based on whether it can be scratched by a substance of known hardness.
The 10 standard minerals of the Mohs hardness scale from softest to hardest are talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum and diamond. The Mohs hardness scale is an excellent tool for identifying minerals. It is a comparative scale. Other methods are also used to identify minerals, such as luster, color, crystalline form and cleavage.