Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Mineralogical Magazine Don't get GSW? Talk to your librarian.
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Mineralogical Magazine; October 2003; v. 67; no. 5; p. 957-965; DOI: 10.1180/0026461036750153
© 2003 Mineralogical Society of Great Britain and Ireland
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
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (1)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Reguir, E. P.
Right arrow Articles by Mitchell, R. H.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Pb-bearing hollandite-type titanates: A first natural occurrence and reconnaissance synthesis study

E. P. Reguir1, A. R. Chakhmouradian1,* and R. H. Mitchell2

1 Department of Geological Sciences, University of Manitoba, 125 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada
2 epartment of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario, P7B 5E1, Canada

* E-mail: chakhmou{at}ms.umanitoba.ca

Some samples of hollandite-type titanates from the Murun alkaline complex (Yakutia, Russia) contain appreciable amounts of Pb (up to 12.5 wt.% PbO). These titanates occur in a pegmatitic K-feldspar-aegirine rock containing subordinate K-rich batisite, titanite, wadeite and other minerals. The Pb-bearing crystals coexist with hollandite-type phases devoid of detectable Pb and zoned from a K-dominant (priderite) core to a Ba-dominant (henrymeyerite) rim. Recalculation of the microprobe analyses on the stoichiometric basis indicates that most of the Fe occurs in this mineral in trivalent form, suggesting the existence of a solid solution between the Ba(Ti6Fe23+)O16, K2(Ti6Fe23+)O16 and Pb(Ti6Fe23+)O16 end-members. The maximum proportion of the latter end-member in the Murun titanates is ~45 mol.%. The Ba-free compositions [Pb1.0–1.3(Ti,Fe)8O16] and intermediate members of the (Ba1–xPbx)(Ti6Fe23+)O16 series were synthesized at 1050–1100°C. The synthesis products comprise tetragonal hollandites of various stoichiometry intermixed with rutile, a pseudobrookite-type phase and (for the Ba-free compositions) minor macedonite. Electron microprobe analyses of the hollandites indicate that there is a continuous series of compositions between the two hexatitanate end-members, Ba(Ti6Fe23+)O16 and Pb(Ti6Fe23+)O16. The crystal structure of one intermediate member was refined by the Rietveld method in space group I4/m, and found to differ from the hollandite archetype (i.e. Pb-bearing Ba manganate) in that Pb is preferentially partitioned into the 2b tunnel site at (0,0,1/2), whereas Ba is partitioned into the larger 4e site at (0,0,~0.8).

KEYWORDS: hollandite, cryptomelane group, titanate, alkaline pegmatite, Murun complex, Yakutia, synthesis, structure, cation ordering




This article has been cited by other articles:


Home page
 Reviews in Mineralogy and GeochemistryHome page
M. Pasero
A Short Outline of the Tunnel Oxides
Reviews in Mineralogy and Geochemistry, January 1, 2005; 57(1): 291 - 305.
[Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Mineralogical Society of Great Britain and Ireland