Diatomite is a sedimentary rock, very porous and absorbent, with a cell membrane forming siliceous. It is massive, stratified, pulverulent, very light, and bulky, forming layers little or very contaminated with impurities, such as organic matter, clays, sand, iron oxide, calcium and magnesium carbonate, volcanic ash, sponge spicules, and other materials in smaller quantities. Colors: white, cream, gray, brown, and greenish.