Argillation of Three Silicate Rocks Expressed in Terms of Ion Transfer

W. D. Keller, G. A. Kiersch and Paul Howell
University of Missouri and University of Arizona

Abstract: The transfer of ions during the weathering of a Medford diabase, a granite from British Guiana, and of the Cheto Arizona tuff is traced by recasting the analyses of the fresh rocks and their altered counterparts into 160-oxygen rock cells, and by comparing algebraically the products of the weathering reaction with the original reactants.

Hydrolysis and hydration are the first steps in the reaction. H ions were added in the weathering environment of the diabase and granite, but Mg ions were added in the change of tuff to bentonite.

Silica and alkali metal ions are dissolved and removed during weathering of the diabase and granite, presumably under acid conditions, but it appears that the Cheto tuff was formed under a non-acid environment where Mg was added. During the hydrolysis of silicate rocks, H ions are concentrated temporarily in the clay minerals on land, while OH ions go to the ocean.

More examples of ion transfer during weathering than the three given herein are needed to define the reactions occurring in the many environments of alteration which rocks encounter.

Clays and Clay Minerals; 1954 v. 3; no. 1; p. 413-420; DOI: 10.1346/CCMN.1954.0030134
© 1954, The Clay Minerals Society
Clay Minerals Society (www.clays.org)