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Channel constituents in cordierite

Goldman, Don S. and Rossman, George R. and Dollase, Wayne A. (1977) Channel constituents in cordierite. American Mineralogist, 62 (11-12). pp. 1144-1157. ISSN 0003-004X. http://resolver.caltech.edu/CaltechAUTHORS:20130513-113501853

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Abstract

Chemical, optical and infrared absorption, Mössbauer and X-ray data are reported for eight cordierite samples. Fe^(2+) in the octahedral and channel sites is identified in optical and Mössbauer spectra, which indicate that generally less than 5 percent of the total iron is Fe^(2+) in the channels. The single-crystal Mössbauer data of Duncan and Johnston (1974) are reinterpreted. Two types of H_2O are identified and are found to be oriented in the (100) plane with their H-H directions parallel to [001] (Type I) and [010] (Type II). Type II H_2O is found to correlate to the amount of cations in the channels. Optical spectra provide a measure of the hexagonality of cordierite, but these measurements are not correlated with the distortion index, Δ. The color and pleochroism are suggested to arise from intervalence charge-transfer between octahedral Fe^(2+) and channel Fe^(3+). The strong enhancement of intervalence intensity after dehydration is interpreted in terms of migration of Fe^(2+) from the six-membered tetrahedral rings to the walls of the channel cavities. It is proposed that migration of cations, mainly Na^+, from the rings into the cavities is primarily responsible for changes in the distortion index which accompany dehydration. Values of є (molar absorptivity) for the H_2O absorption bands are determined.


Item Type:Article
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http://www.minsocam.org/msa/collectors_corner/amtoc/toc1977.htmPublisherUNSPECIFIED
Additional Information:© 1977 Mineralogical Society of America. Manuscript received, January 10, 1977; accepted for publication, June 7, 1977. We thank G. V. Gibbs (Virginia Polytechnic Institute and State University), E. P. Meagher (University of British Columbia), R. F. Dymek (California Institute of Technology), J. H. Berg (University of Massachusetts), R. H. Currier (San Marino, California), and J . F. Duncan (Wellington, New Zeal and) for supplying many of the samples used in this study. We are especially indebted to R. M. Houseley (Rockwell International) for obtaining the Mössbauer data. In addition, we thank G. V. Gibbs, E. P. Meagher, G. E. Brown (Stanford University), and J. H. Stout (University of Minnesota) for discussing many of the results. This research was supported, in part, by NSF Grants DES 74-19918 and EAR 76-02014.
Funders:
Funding AgencyGrant Number
NSFDES 74-19918
NSFEAR 76-02014
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Caltech Division of Geological and Planetary Sciences2843
Record Number:CaltechAUTHORS:20130513-113501853
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130513-113501853
Official Citation:Channel constituents in cordierite Don S. Goldman, George R. Rossman and Wayne A. Dollase 1144-1157
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38448
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:13 May 2013 19:03
Last Modified:13 Feb 2019 18:05

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