In mineralogy, in which science the hardness is an important characteristic, ten bodies are usually taken as points of comparison-the softest being termed 1 and the hardest 10. These are: 1, talc; 2, gypsum; 3, carbonate of lime; 4, fluor-spar; 5, phosphate of lime; 6, felspar; 7, quartz; 8, topaz; 9, corundum; 10, dia mond. Hence, when scientific works speak of the hardness of a body being 6, 8, 4, etc., reference is made to the relative hardness expressed by the list above given.

The tenacity of metals is estimated by the resistance which wires of the same diameter experience when passed at equal temperature through the same hole of a draw-bench. The following-table gives the relative tenacity of various metals and alloys: Steel already drawn, 100; iron already drawn, 88; brass already drawn, 77; gold at 0.875, annealed, 73; steel annealed, 65; copper already drawn, 68; silver at 0.750, annealed, 58; silver at 0.875, 54; brass annealed, 46; iron annealed, 43; platinum annealed, 38; copper annealed, 38; fine gold annealed, 37; fine silver annealed, 37; zinc, 34; tin, 11; lead, 4.