Synthesis of Clay Minerals at Low Temperatures

S. Henin
Soils Laboratory, Versailles, France

Abstract: Numerous attempts have shown that it seems to be impossible to crystallize co-precipitates of silica and hydroxides; we therefore attempted to prepare clay minerals starting from solutions of their constituents. By allowing these dilute solutions (tenths of milligrams per liter) to pass slowly into a flask containing distilled water, it has been possible to prepare substances similar to clay minerals. These have been identified by x-rays, chemical analysis, dehydration curves, and electron micrographs.

Using as cations Mg, Fe2+, Fe3+, and Ni, minerals of the montmorillonite type have been prepared for various pH values (generally greater than 7). Below this value, depending on the cations; oxides, hydroxides, or amorphous materials are obtained.

Under certain conditions in the absence of silica the glass vessel was attacked, and antigorites of Mg and Ni were then obtained. Always when the supply of silica was small, and with the cation introduced in the form of a very dilute solution, the process gave rise to montmorillonite. In the presence of K, illites were sometimes formed.

The method seems to be of very general application. Only the purely aluminum minerals offer difficulties of preparation. The significance of these results is discussed.

Clays and Clay Minerals; 1955 v. 4; no. 1; p. 54-60; DOI: 10.1346/CCMN.1955.0040108
© 1955, The Clay Minerals Society
Clay Minerals Society (www.clays.org)