: a scale of hardness for minerals in which 1 represents the hardness of talc; 2, gypsum; 3, calcite; 4, fluorite; 5, apatite; 6, orthoclase; 7, quartz; 8, topaz; 9, corundum; and 10, diamond
: a revised and expanded version of the original Mohs' scale which provides finer distinctions between the harder materials and in which 1 represents the hardness of talc; 2, gypsum; 3, calcite; 4, fluorite; 5, apatite; 6, orthoclase; 7, vitreous pure silica; 8, quartz; 9, topaz; 10, garnet; 11, fused zirconium oxide; 12, fused alumina; 13, silicon carbide; 14, boron carbide; and 15, diamond
Biographical Note for MOHS' SCALE
Mohs\ˈmōs\Friedrich(1773–1839), German mineralogist. Mohs's chief scientific contribution was establishing systematic mineralogy on a new basis. He was placed in charge of several important mineral collections, of which he later published systematic descriptions. In the early 1820s he developed a new method of mineral classification that focused on the arrangements of minerals in crystal systems based on external symmetry. In 1812 he introduced the Mohs' scale of hardness for minerals. By the 1820s the scale had been widely adopted by other mineralogists.