Emery, also known as silicon carbide (SiC), is made of quartz sand, petroleum coke (or coal coke), 

wood chips (salt is added when producing green silicon carbide) and other raw materials by high temperature smelting through resistance furnace. 

Silicon carbide is also a rare mineral in nature, mosanite. Silicon carbide is also called carbon silica. In contemporary C, N, B and other non-oxide high-tech refractory raw materials, 

silicon carbide is the most widely used and the most economical kind, which can be called gold and steel sand or refractory sand. 

At present, the industrial production of silicon carbide in China is divided into black silicon carbide and green silicon carbide,

 both of which are hexagonal crystals with a specific gravity of 3.20~3.25 and a microhardness of 2,840 ~ 3,320 kg/mm2.