Choose The Right Diamond Core Drilling Machine
2017-1-18 · The units of hardness are expressed as numbers ranging from 1 to 10, each of which is represented by a mineral that can be made to scratch any other mineral bearing a lower number. In ascending order of hardness, the minerals are ranked as follows: Talc (1), Gypsum (2), Calcite (3), Fluorite (4), Apatite (5), Orthoclase (6), Quartz (7), Topaz (8), Corundum (9) and Diamond (10).
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