"Rock Tumbler grit", also known as "rock polishing grit", is usually a silicon carbide powder that is much harder than the types of rocks that are commonly polished within a rock tumbler. If it is tumbled within a barrel with rocks and water the abrasion caused from the grit particles https://siliconcarbideprotectingt25803.plpwiki.com/6179417/the_ultimate_guide_to_silicon_carbide_bipolar_transistor