The Oxidation of Octahedral Iron in Biotite

R. J. Gilkes, R. C. Young and J. P. Quirk
Department of Soil Science and Plant Nutrition, Institute of Agriculture, University of Western Australia, Nedlands, Western Australia 6009

Abstract: Oxidation of octahedral ferrous iron in biotite by saturated bromine water results in a loss of both octahedral and interlayer cations. The hydroxyl adjacent to vacant octahedral cation sites adopt an inclined orientation resulting in a more stable environment for interlayer cations. The only structural change accompanying these processes is a decrease in b-axis dimension which is linearly related to octahedral ferric iron content. These findings are in agreement with observations made on naturally weathered biotites.

Clays and Clay Minerals; October 1972 v. 20; no. 5; p. 303-315; DOI: 10.1346/CCMN.1972.0200507
© 1972, The Clay Minerals Society
Clay Minerals Society (www.clays.org)