Bentonites
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
Bentonites
colloidal clays that consist primarily of minerals of the montmorillonite group—Al2[Si4O10](OH)2 nH20. The formation of bentonites results from the chemical alteration of volcanic rock (tuffs and ashes), apparently under conditions of the sea floor. Bentonites are widely used in the petroleum industry for the production of boring solutions, as bleaching clays, and as cementing material in foundry molding sands and ceramic bodies. The largest bentonite deposits in the USSR are found in Turkmenia and Georgia; the largest deposits abroad are in the USA, Mexico, Italy, and Rumania.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.