Thermal Decomposition of Amosite, Crocidolite, and Biotite

P. G. Rouxhet1, J. L. Gillard and J. J. Fripiat2
Laboratoire de Physico-Chimie Minérale, de Croylaan 42, 3030 Heverlee, Belgium
1Chargé de recherche du F.N.R.S.
2Université Catholique de Louvain and M.R.A.C. (Tervuren).

Summary: The oxidation of amosite, crocidolite, and biotite has been determined at temperatures up to nearly 900 °C under both a vacuum (10−2 mm Hg) and oxygen (10 and 600 mm Hg). Infrared spectra gave the loss of constitutional hydroxyl under these conditions. The loss of tensile strength of the amphiboles with increasing temperature seems to be due to thermal decomposition. For the three minerals oxidation takes place progressively over a broad temperature range. Under vacuum there is a certain temperature above which the ferric iron previously formed is reduced; this temperature corresponds to the completion of the loss of hydroxyl. The crocidolite anhydride in the literature is most probably an oxycrocidolite formed by dehydrogenation, the truly dehydroxylated zones being amorphous.

Mineralogical Magazine; March 1972 v. 38; no. 297; p. 583-592; DOI: 10.1180/minmag.1972.038.297.07
© 1972, The Mineralogical Society
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