Anthracite latter in two or three sizes, all three being above in (38 mm) size on round-hole screens. High grade (HG) and ultra high grade (UHG) anthracite are the highest grades of anthracite coal. They are the purest forms of coal, having the highest degree of coalification, the highest carbon count and energy content and the fewest impurities (moisture, ash and volatiles). High grade and ultra high grade anthracite are harder than standard grade anthracite, and have a higher relative density. An example of a chemical formula for high-grade anthracite would be CHONS, representing 94% carbon. UHG anthracite typically has a
Carbon, Iowa originally named Walters, after its first settler, but was renamed Carbon after the discovery of coal. The town was established in 1873, but was not incorporated until 1903. A post office was established in Carbon in 1874, but from 1877 to 1880, the name was changed to Shinn. By the time of the Civil War, there were small coal mines along the riverbanks near Carbon. In 1894, there were 9 coal mines in Carbon, of which 5 were in current use. Typical mine shafts were 80 feet deep, working a coal seam 12 to 20 inches (30 to 50 cm)