kieselgur
/ˈkiːzəlɡʊr/
noun
- A soft, light-colored sedimentary rock made from the fossilized remains of tiny aquatic organisms called diatoms; used in filters, abrasives, and as an absorbent.
- Gardeners sometimes mix kieselgur into soil to improve drainage.
- In the 19th century, kieselgur was used to make lightweight bricks for building.
- The pool filter uses kieselgur to trap tiny particles and keep the water clean.
Synonyms