Diatomaceous earth (pronounce /ˌdaɪətəˈmeɪʃəs ˈɝθ/), also known as DE, TSS, diatomite, diahydro, kieselguhr, kieselgur and celite) is a naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder. This powder has an abrasive feel, similar to pumice powder, and is very light, due to its high porosity. The typical chemical composition of diatomaceous earth is 86% silica, 5% sodium, 3% magnesium and 2% iron.