Fibrous nanoinclusions in massive rose quartz: HRTEM and AEM investigations
- Creators
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Ma, Chi
- Goreva, Julia S.
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Rossman, George R.
Abstract
Pink fibrous crystals within massive rose quartz from localities in California, South Dakota, Brazil, Madagascar, and Namibia were examined with high-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM). This study reveals that the nanofibers in all samples are related to dumortierite. Selected-area electron diffraction (SAED) patterns and HRTEM images indicate that the dumortierite-related fibers have a superstructure with a doubled periodicity along the a and b axes of dumortierite, giving cell parameters a = 2a_(dum) = 2.36 nm, b = 2b_(dum) = 4.05 nm, c = c_(dum) = 0.47 nm. Computer simulations suggest that periodic arrangements of two different M1 site occupancies in the octahedral face-sharing chains give rise to the superstructure. One type of M1 site is occupied mainly by Al, whereas the other type is dominated by Ti and Fe. Simulated HRTEM images based on our proposed model match the experimental images. Most of the fibers, elongated along the c axis, are free of defects. AEM analysis shows that the dumortierite-related fibers have a composition similar to well-characterized dumortierite, but that they contain a greater amount of Fe substituting for Al in the M1 sites. Boron was detected in all fibers examined by electron energy loss spectroscopy as well as in sillimanite crystals found as a minor component in one rose quartz from Brazil.
Additional Information
© 2002 American Mineralogist. Manuscript received April 4, 2001; Manuscript accepted November 12, 2001. Manuscript handled by Adrian J. Brearley. We thank Ulrich Dahmen and Christian Kisielowski for allowing us to access the ARM and the JEOL 200CX microscopes at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Roar Kilaas for helping with the NCEMSS image simulation program, Chengyu Song for assisting with the ARM operation, and Thomas George for allowing us to use the ISI 200 kV HRTEM at the Jet Propulsion Laboratory. Lothar Jung (Quartz Technology, Inc.) provided samples for this study and several stimulating discussions in the early stages of this project. Rock H. Currier (Jewel Tunnel Imports) and Edward Swobota (Beverly Hills, CA) also provided samples that were critical for this study. Careful reviews by Peter Heaney and Mike Zolensky led to a significant improvement in the quality of the manuscript. Primary funding for this project was provided by the White Rose Foundation with additional funding from the National Science Foundation through grant NSF EAR-9804871.Additional details
- Eprint ID
- 37979
- Resolver ID
- CaltechAUTHORS:20130417-073749432
- White Rose Foundation
- EAR-9804871
- NSF
- Created
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2013-04-17Created from EPrint's datestamp field
- Updated
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2020-03-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences