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
Bituminous coal sulfur, and other impurities as possible. The constituents of the coal should be as follows: Cannel coal is a coal which ignites easily producing a bright flame. The name derives from the Scottish pronunciation of "candle coal". It contains a high volatile content, is non-coking and was a source for coal oil in West Virginia during the mid-1800s. While the use of Cannel has greatly diminished over the past century, it is still valued by artists for its ability to be carved and polished into sculptures and jewelry. When used for many industrial processes, bituminous coal must first be "coked"