The Things you set into your tumbler particularly to shine the rocks in the ultimate stage is often made of cerium oxide, tin oxide, chrome oxide, or aluminum oxide. It is just a sort of grit traditionally known as a polishing compound and is extremely fine. High hardness, superior modulus https://www.quora.com/profile/Trevor-Flatcher-2/Advantages-and-Challenges-of-Silicon-Carbide-Specialty-Ceramics-Macrocosm-Materials-Company-Overview-Founded-in-2016-1