Friedrich Mohs harder. This became the basis of the hardness scale developed by Mohs. The hardest mineral, diamond was given a value of 10 and softer minerals such as talc were given the very low value of 1 (unity). Other minerals were given intermediate values, depending on their ability to scratch another mineral in the scale. Thus gypsum was given the value 2 because it will scratch talc crystals, and calcite the value 3 because it will scratch gypsum. Minerals are also now classified by chemical characteristics, but the physical properties are still useful in field examination. In 1812, Mohs became a
Mineral Point, Wisconsin county seat of Iowa County was relocated to nearby Dodgeville, Wisconsin, where it remains today. Afterwards there was an intense rivalry between the two cities, during which Mineral Point fired a cannon towards Dodgeville's direction. As lead mining declined in Mineral Point, zinc mining and smelting became important new industries. Zinc ore was discovered with increasing frequency near the bottoms of old lead mines. The Mineral Point Zinc Company was founded in 1882, and by 1891 it was operating the largest zinc oxide works in the United States at Mineral Point. Zinc mining and processing continued on a large scale