Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (16) Citing Articles via Google Scholar Google Scholar Articles by Berlepsch, P. Articles by Graeser, S. Search for Related Content GeoRef GeoRef Citation

Tripuhyite, FeSbO₄, revisited

¹ Laboratorium für chemische und mineralogische Kristallographie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
² The South Australian Museum & Department of Geology and Geophysics, The University of Adelaide, North Terrace, 5000 Adelaide, South Australia
³ Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
⁴ Mineralogisch-Petrographisches Institut, Universität Basel, Bernoullistrasse 30, CH-4056 Basel, Switzerland

^* E-mail: peter.berlepsch{at}krist.unibe.ch

The exact nature of tripuhyite remains controversial more than 100 years after the first description of the mineral. Different stoichiometries and crystal structures (rutile or tri-rutile types) have been suggested for this Fe-Sb-oxide. To address these uncertainties, we studied tripuhyite from Tripuhy, Minas Gerais, Brazil (type material) and Falotta, Grisons, Switzerland using single-crystal and powder X-ray diffraction (XRD), optical microscopy and electron microprobe analysis.

Electron microprobe analyses showed the Fe/Sb ratios to be close to one in tripuhyite from both localities. Single crystal XRD studies revealed that tripuhyite from the type locality and from Falotta have the rutile structure (P4₂/mnm, a = 4.625(4) c = 3.059(5) and a = 4.6433(10) c = 3.0815(9) Å , respectively). Despite careful examination, no evidence for a tripled c parameter, characteristic of the tri-rutile structure, was found and hence the structure was refined with the rutile model and complete Fe-Sb disorder over the cationic sites in both cases (type material: R₁ = 3.61%; Falotta material: R₁ = 3.96%). The specular reflectance values of type material tripuhyite and lewisite were measured and the following refractive indices calculated (after Koenigsberger): tripuhyite n_min = 2.14, n_max = 2.27; lewisite (cubic) n = 2.04.

These results, together with those of ⁵⁷Fe and ¹²¹Sb Mössbauer spectroscopy on natural and synthetic tripuhyites reported in the literature, indicate that the chemical formula of tripuhyite is Fe³⁺Sb⁵⁺O₄ (FeSbO₄). Thus, tripuhyite can no longer be attributed to the tapiolite group of minerals of general type AB₂O₆. A comparison of the results presented with the mineralogical data of squawcreekite suggests that tripuhyite and squawcreekite are identical. In consequence, tripuhyite was redefined as Fe³⁺Sb⁵⁺O₄ with a rutile-type structure. Both the proposed new formula and unit cell (rutile-type) of tripuhyite as well as the discreditation of squawcreekite have been approved by the Commission on New Mineral and Mineral Names (CNMMN) of the International Mineralogical Association (IMA).

KEYWORDS: tripuhyite, squawcreekite, lewisite, structure refinements, ore microscopy, electron microprobe analyses

This article has been cited by other articles:

				C. J. Stanley, G. C. Jones, M. S. Rumsey, C. Blake, A. C. Roberts, J. A.R. Stirling, G. J.C. Carpenter, P. S. Whitfield, J. D. Grice, and Y. Lepage Jadarite, LiNaSiB3O7(OH), a new mineral species from the Jadar Basin, Serbia European Journal of Mineralogy, July 1, 2007; 19(4): 575 - 580. [Abstract] [Full Text] [PDF]

				L. B. Railsback Patterns in the compositions of oxysalt and sulfosalt minerals, and the paradoxical nature of quartz American Mineralogist, February 1, 2007; 92(2-3): 356 - 369. [Abstract] [Full Text] [PDF]

				A. G. Christy and K. Gatedal Extremely Pb-rich rock-forming silicates including a beryllian scapolite and associated minerals in a skarn from Langban, Varmland, Sweden Mineralogical Magazine, December 1, 2005; 69(6): 995 - 1018. [Abstract] [Full Text] [PDF]

				M. Novak, P. Cerny, J. Cempirek, V. Srein, and J. Filip FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb) Can Mineral, August 1, 2004; 42(4): 1117 - 1128. [Abstract] [Full Text] [PDF]

				C. J. Stanley, C. J. Stanley, and D. J. Vaughan ALAN J. CRIDDLE DSc 1944-2002: Memorial Notice Mineralogical Magazine, April 1, 2004; 68(2): 223 - 229. [Full Text] [PDF]