Mica Weathering Rates as Related to Mica Type and Composition*

R. A. Leonard and S. B. Weed
Department of Soil Science, North Carolina Agricultural Experiment Station, North Carolina State University, Raleigh, N.C. 27607
* Published with the approval of the Director as Paper No. 2929 of the Journal Series.
Research Soil Scientist, USDA, Watkinsville, Georgia 30677 (formerly Instructor, Department of Soil Science, North Carolina State University, Raleigh, North Carolina.
Professor of Soils, North Carolina State University, Raleigh, North Carolina.

Abstract: Potassium release rates from micas varying widely in type and composition were measured. A sodium tetraphenylboron solution was used as the extracting agent. Muscovites were found to be two orders of magnitude more stable than a naturally occurring phlogopite and biotite. Synthetic fluorphlogopite was as stable as some muscovites. Lepidolite was the most stable mica. Primary factors affecting mica stability are thought to be: Hydroxyl bond orientation, isomorphous replacement of OH by F, the stronger Lewis base, and structural factors that lead to compression or stretching of the K—O bond.

Clays and Clay Minerals; November 1970 v. 18; no. 4; p. 187-195; DOI: 10.1346/CCMN.1970.0180402
© 1970, The Clay Minerals Society
Clay Minerals Society (www.clays.org)