The Oxidation of Octahedral Iron in Biotite

R. J. Gilkes
1972 Clays and clay minerals  
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
more » ... tions made on naturally weathered biotites.
doi:10.1346/ccmn.1972.0200507 fatcat:6gygkgkpdrhwpowoz4rtu37f7e