dīˈad.əˌmīt noun
( -s )
Etymology: International Scientific Vocabulary diatom + -ite
: a light friable siliceous material resembling chalk that is derived chiefly from the remains of diatoms and is used as a filter aid, adsorbent, filler (as for paints and plastics), and abrasive, and for thermal insulation — called also diatomaceous earth ; compare kieselguhr , tripoli