... ,marble,and other soft metal materials. 6''x2''x2'' Green Silicon Carbide Rubbing BrickA very low-cost tool to grind & sharpen sandstone ... materials,etc.Made up of GC (short for Green Sillcon Carbide),an abrasive material softer than Diamond & Aluminum Oxide. Size:length ... /T,L/C,Wetern Union,etc. 6''x2''x2'' Green Silicon Carbide(GC) Rubbing Brick for Stone