The location and content of iron in natural biotites and phlogopites: a comparison of several methods

Abstract

Abstract Mössbauer spectra have been obtained at room temperature on a series of phlogopites and biotites which have also been characterized by chemical analyses, I.R. and N.M.R. The distribution of the Fe 2+ ions on the two possible octahedral sites is on the average nearly random. A clear example of tetrahedrally coordinated Fe 3+ ions in a natural phlogopite is given. This phlogopite has a very high vermiculitization ability. The Fe 3+ content of the samples has been determined by two different chemical methods and it is shown that even when precautions are taken to minimize oxidation, the agreement with Mössbauer spectra is poor.