"Rock tumbler grit", also known as "rock polishing grit", is often a silicon carbide powder that is much harder than the types of rocks that are commonly polished in the rock tumbler. If it is tumbled in a barrel with rocks and water the abrasion caused by the grit particles https://waferboats81470.blog-kids.com/29106273/not-known-details-about-silicon-carbide-heating-elements-technical-data