Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
American Mineralogist Don't get GSW? Talk to your librarian.
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
American Mineralogist; January 2005; v. 90; no. 1; p. 22-27; DOI: 10.2138/am.2005.1654
© 2005 Mineralogical Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Web of Science (3)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Crichton, W. A.
Right arrow Articles by Grzechnik, A.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Evidence for monazite-, barite-, and AgMnO4 (distorted barite)-type structures of CaSO4 at high pressure and temperature

Wilson A. Crichton1,*, John B. Parise2, Sytle M. Antao2 and Andrzej Grzechnik3

1 European Synchrotron Radiation Facility, B. P. 220, F-38043 Grenoble, France
2 Dept Chemistry, Dept Geosciences and MPI, State University of New York, Stony Brook, New York 11794-2100, U.S.A.
3 Laboratory of Crystallography, Universität Bayreuth, Bayreuth D-95440, Germany

Correspondence: * E-mail: crichton{at}esrf.fr

Using laser-heated diamond-anvil cells, we have observed CaSO4 undergoing phase transitions from its ambient anhydrite structure to the monazite type, and at highest pressure and temperature to crystallize in the barite-type structure. On cooling, the barite structure distorts from an orthorhombic to a monoclinic lattice to produce the AgMnO4-type structure. The barite-structured form of CaSO4 that we encounter at high pressure and temperature has been, in particular, long expected as a high- pressure phase of CaSO4-anhydrite from systematic trends of similar AIIBVIO4-type sulfates, selenates, and tellurates, but has not been observed before. Similarly, the monoclinic distortion of the barite structure has itself been proposed as an intermediate phase between anhydrite and barite types through comparison with the phase diagrams of NaBF4 and NaClO4. This result has important consequences for identifying structural trends between different ABO4-type phases of Group II sulfates, selenates, tellurates, chromates, molybdates and tungstates that crystallize in anhydrite, zircon, monazite, barite and scheelite-type structures at ambient and high pressures.






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Mineralogical Society of America