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Published April 2006 | public
Journal Article

Ganterite, the barium mica Ba_(0.5)K_(0.5)Al_2(Al_(1.5)Si_(2.5))O_(10)(OH)_2, from Oreana, Nevada

Abstract

The barium dioctahedral layer silicate, ganterite, was identified from the Lincoln Hill dumortierite deposit near Oreana, Nevada, based on electron microprobe, electron-backscatter diffraction (EBSD), and Raman spectrum microanalyses. This phase occurs with dumortierite, barite, and muscovite in a vein specimen formed by hydrothermal alteration. Back-scattered electron images of the muscovite from this locality show extensive zonation of the BaO content with regions of high Ba concentrations up to 15 μm in dimension. Electron microprobe analyses of these regions reveal a composition (Ba_(0.53)K_(0.37)Na_(0.05))_(∑=0.95) (Al_(2.00)Ti_(0.01))_(∑= 2.01)[Al_(1.51)Si_(2.49)O_(10)](OH)_2 or, ideally, (Ba_(0.5)K_(0.5))Al_2(Al_(1.5)Si_(2.5))O_(10)(OH)_2. This composition corresponds to the recently described mica, ganterite. Complete solid solutions between muscovite and ganterite were observed that range from 0.60% up to 18.12 wt% BaO. The electron-backscatter diffraction and Raman spectra of this phase are essentially indistinguishable from those of muscovite confirming that ganterite has a mica structure.

Additional Information

© 2006 Mineralogical Society of America. Manuscript received August 30, 2005. Manuscript accepted October 22, 2005. Manuscript handled by Sergey Krivovichev. We thank Royal Marshall for having donated the sample used in this study. This project was supported, in part, by the White Rose Foundation and the National Science Foundation through grants EAR-0125767 and EAR-0337816. SEM and electron microprobe analyses were carried out at the Caltech Geological and Planetary Sciences Division Analytical Facility, which is supported in part by the MRSEC Program of the NSF under DMR-0080065. We thank Thomas Armbruster and Sergey Britvin for their constructive reviews, and Sergey Krivovichev for handling this manuscript.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023