Lortone Silicon Carbide Grit 46/70 Mesh Extra Coarse Rotary Tumbling Medium - 50 lb 591-053

"Tumbler grit" is a silicon carbide powder that is much harder than the types of rocks that are commonly tumbled. If it is tumbled in a barrel with rock and water the abrasion caused by the grit particles rounds the sharp edges off of the rocks. We use about four tablespoons of grit in a three-pound capacity tumbler barrel..