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Crystal structure and revised chemical formula for burckhardtite, Pb_2(Fe^(3+)Te^(6+))[AlSi_3O_8]O_6: a double-sheet silicate with intercalated phyllotellurate layers

Christy, Andrew G. and Kampf, Anthony R. and Mills, Stuart J. and Housley, Robert M. and Thorne, Brent (2014) Crystal structure and revised chemical formula for burckhardtite, Pb_2(Fe^(3+)Te^(6+))[AlSi_3O_8]O_6: a double-sheet silicate with intercalated phyllotellurate layers. Mineralogical Magazine, 78 (7). pp. 1763-1773. ISSN 0026-461X. http://resolver.caltech.edu/CaltechAUTHORS:20150616-132158306

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Abstract

The crystal structure of burckhardite from the type locality, Moctezuma, Sonora, Mexico, has been refined to R_1 = 0.0362 and wR_2 = 0.0370 for 215 reflections with I > 2σ(I). Burckhardtite is trigonal, space group P3lm, with the unit-cell parameters ɑ = 5.2566(5) Å, c = 13.0221(10) Å, V = 311.62(5) Å3 and Z = 1 for the ideal formula unit Pb_2(Fe^(3+)Te^(6+))[AlSi_3O_8]O_6. There is no long-range order of (Fe^(3+), Te^(6+)) or (Al^(3+), Si^(4+)). New microprobe data were used to estimate site scattering factors, and Raman spectroscopic data showed no evidence of O–H stretching bands. Burckhardtite is not closely related to the micas, as supposed previously, but is a double-sheet silicate in which the aluminosilicate anion resembles that of minerals such as cymrite and kampfite. The [(Fe^(3+)Te^(6+))O_6]^(3−) part of the structure is not bonded directly to the aluminosilicate layer, but forms a discrete anionic phyllotellurate layer that alternates with the [AlSi_3O_8]^− double sheets. Similar phyllotellurate layers are known from several synthetic phases. In burckhardtite, Pb^(2+) cations intercalate between phyllosilicate and phyllotellurate layers, forming a Pb_2[FeTeO_6] module that is topologically similar to a slab of the structure of rosiaite, Pb[Sb_2O_6]. The crystal symmetry, structure, classification as a double-sheet silicate and chemical formula, including the determination of the 6+ valence of Te and absence of essential H_2O, are all new findings for the mineral.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1180/minmag.2014.078.7.18DOIArticle
http://minmag.geoscienceworld.org/content/78/7/1763PublisherArticle
Additional Information:© 2014 The Mineralogical Society. Received 5 May 2014; Accepted 27 June 2014; Associate Editor: E. Grew. The authors thank Fernando Cámara, Peter Leverett, Peter Williams and an anonymous reviewer for helpful suggestions which improved the manuscript. Part of this study has been funded by the Ian Potter Foundation grant "tracking tellurium" to SJM which we acknowledge gratefully. The X-ray diffraction study was funded by the John Jago Trelawney Endowment to the Mineral Sciences Department of the Natural History Museum of Los Angeles County and microprobe and Raman analyses were funded by a grant from the Northern California Mineralogical Association.
Funders:
Funding AgencyGrant Number
Ian Potter FoundationUNSPECIFIED
John Jago Trelawney EndowmentUNSPECIFIED
Northern California Mineralogical AssociationUNSPECIFIED
Subject Keywords:crystal structure, burckhardtite, phyllotellurate, phyllosilicate, double-sheet silicate, Moctezuma.
Record Number:CaltechAUTHORS:20150616-132158306
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150616-132158306
Official Citation: Andrew G. Christy, Anthony R. Kampf, Stuart J. Mills, Robert M. Housley, and Brent Thorne Crystal structure and revised chemical formula for burckhardtite, Pb2(Fe3+Te6+)[AlSi3O8]O6: a double-sheet silicate with intercalated phyllotellurate layers Mineralogical Magazine, December 2014, v. 78, p. 1763-1773, published online February 27, 2015, doi:10.1180/minmag.2014.078.7.18
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58284
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:16 Jun 2015 21:57
Last Modified:19 May 2017 15:54

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