Brown fused aluminum oxide 800 mesh grit. 7 micron. Fine abrasive powder. For use in all types of rock tumblers and for lapping as a pre-polish or an additional pre-polish before the polish stage. Chemical makeup according to the manufacturer is as follows 96% aluminum oxide, 2.7% titanium dioxide, silicon dioxide .7%, iron oxide .1%, calcium oxide .15%, magnesium oxide .3%.