a soft very fine-grained whitish rock consisting of the siliceous remains of diatoms deposited in the ocean or in ponds or lakes. It is used as an absorbent, filtering medium, insulator, filler, etc
See also diatomaceous earth
diatomite in American English
(daɪˈætəˌmaɪt)
noun
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.