Moh's hardness scale compared to indentation hardness

        graphite
1       talc
2       gypsum
3       calcite fingernail = 2.5 copper coin = 3
4        fluorite
5         apatite   pocket knife, glass = 5.5
6           orthoclase
7             quartz    steel file
8                   Topaz
9                               Corundum
10                                                              diamond
         0000 1000  2000  3000  4000  5000  6000  7000  8000
                       ABSOLUTE HARDNESS

How is hardness testing done? Learn to test the hardness of a mineral:

*NOTE* The hardness of quartz is 7.0 not 6.0, as claimed in this linked demonstration!