A qualitative scale for hardness in minerals, based on the ability or inability of ten minerals to scratch one another: the harder the mineral, the higher the value on the Mohs scale. The minerals used are: (1) talc; (2) gypsum; (3) calcite; (4) fluorite; (5) apatite; (6) orthoclase feldspar; (7) quartz; (8) topaz; (9) corundum; and (10) diamond. This scale was devised by the German mineralogist Friedrich Mohs (1773–1839) in 1812. There are other, more quantitative, scales for characterizing the hardness of materials.