1773-1839

German geologist best known for developing the Mohs Hardness Scale. Mohs presented his system for classifying minerals in Outline of Mineralogy, published in 1822. This same volume contained a description of his hardness scale, used to compare the hardness of various minerals as a way to help identify them. Still in use today, the Mohs scale ranges from hardness of 1 (talc) through 10 (diamond).