Silicon Carbide is the hardest and sharpest of the minerals used in coated abrasives. It's hardness and sharpness make it ideal abrasive for sanding glass, rubber, plastic, fibrous wood, non-ferrous metals (aluminium, brass, bronze, etc), enamel and other relatively soft materials. 

Silicon carbide is superior to any other abrasive in its ability to penetrate and cut faster under light pressure.