Silicon Carbide is produced by heating silica sand and a carbon source, typically petroleum coke, to high temperatures in a large, open Acheson furnace. The result of this high temperature process is the crystalline formation of Silicon Carbide grains, of both Green and Black coloring. The color difference is due to the purity of the silicon carbide, green SiC being higher purity due to its closer proximity to the heat source of the furnace.