Ferric Tourmaline from Mexico
- 3 April 1964
- journal article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 144 (3614) , 71-73
- https://doi.org/10.1126/science.144.3614.71
Abstract
Dark brown crystals, up to 10 mm long, occur in rhyolite at Mexquitic, San Luis Potosi, Mexico. They are short prismatic, showing {1120}, {3030}, {1011}, {0221}, with c/a 0.4521, measured with a goniometer, and distinct {1120} cleavage. With an unusual combination of cell dimensions, high density, high refractive indices, and extreme birefringence, this tourmaline falls outside the known elbaite-schorl and schorl-dravite series. A chemical analysis, recalculated on the basis of cell volume and density, gives close to the theoretical 150 atoms per cell, whether the iron is ferrous or ferric, but the physical properties indicate a ferric tourmaline.Keywords
This publication has 3 references indexed in Scilit:
- Stability Relations of the Ferruginous Biotite, AnniteJournal of Petrology, 1962
- Structural mechanism of thermal and compositional transformations in silicatesZeitschrift für Kristallographie, 1959
- The determination of the crystal structure of tourmalineActa Crystallographica, 1950