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(diatomaceous earth, infusorial earth, kieselguhr, mountain meal), a sedimentary rock consisting primarily of the shells of diatoms. It is usually friable or weakly cemented and light gray or yellowish in color. Small spheres (globules) of opal of nonorganogenic structure and detrital and argillaceous minerals may be found in diatomite in different quantities. Chemically, diatomite consists of 96 percent hydrated silica (opal). It is highly porous, has a high adsorption capacity, conducts heat and sound poorly, is not easily fused, and is acid resistant. Diatomite is formed from diatomaceous silt that has accumulated in seas and lakes. In a stratigraphic cross section it may be found beginning with the Cretaceous system and is common in Cenozoic beds. Owing to the high solubility of the diatom skeletons it changes easily into tripoli and opoka.
There are deposits of diatomite in the Far East, on the Eastern slope of the Urals, and in the central Volga Region. Diatomite is used as an adsorbent and filter in the textile, petrochemical, and food industries and in the production of antibiotics, paper, various plastics, and dyes. It is also used as a raw material in the making of water glass and glaze, as a heat-and sound-insulating material in construction, as an admixture in certain types of cement, as a polishing agent (in paste form) for metals and marble, and as a pesticide.
REFERENCESShvetsov, M. S. Petrografiia osadochnykh porod, 3rd ed. Moscow, 1958.
Prirodnye sorbenty. Moscow, 1967.
G. A. KALEDA