diatomite[dī at′ə mīt′]
a light-colored, soft sedimentary rock formed mainly of the siliceous shells of diatoms and used in a finely pulverized state as an abrasive, absorbent, filter, etc.
also called diatomaceous earth
A fine, powdered diatomaceous earth used in industry as a filler, a filtering agent, an absorbent, a clarifier, and an insulator. Also called kieselguhr.