Iron redox reactions in the tourmaline structure: High-temperature treatment of Fe3+-rich schorl

Investor logo

Warning

This publication doesn't include Faculty of Economics and Administration. It includes Faculty of Science. Official publication website can be found on muni.cz.
Authors

FILIP Jan BOSI Ferdinando NOVÁK Milan SKOGBY Henrik TUČEK Jiří ČUDA Jan WILDNER Manfred

Year of publication 2012
Type Article in Periodical
Magazine / Source Geochimica et Cosmochimica Acta
MU Faculty or unit

Faculty of Science

Citation
Doi http://dx.doi.org/10.1016/j.gca.2012.02.031
Field Geochemistry
Keywords crystal-structure; heat-treatment; ferric-iron; chemical-composition; site occupancies; dravite series; Mn-tourmaline; chemistry; Mössbauer; Fe
Description We present a detailed study of thermally-driven oxidation and reduction of Fe in the structure of schorl (as the most widespread tourmaline), Fe2+-bearing olenite and fluor-schorl. The principal Fe3+-rich tourmaline investigated in this study is a natural schorl sample from a unique occurrence in peralkaline rocks near Cancrinite Hill, east of Bancroft, southern Ontario. Tourmaline samples were thermally-treated in air and hydrogen at temperatures of 700, 800 and 900 C to oxidize or reduce the structural Fe. High-temperature changes were continuously monitored using 57Fe Mössbauer and infrared spectroscopy. Proportions of Fe2+ and Fe3+ vary as a function of the heat treatment. An increase in Fe3+ up to 100% after heating in air at 700 C was observed, whereas only small changes in the Fe3+/Fetot ratio after heating under hydrogen at 700 C was revealed. Partial deprotonation/protonation represents charge compensation for the oxidation/reduction of Fe at the Y and Z sites.
Related projects:

You are running an old browser version. We recommend updating your browser to its latest version.