Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Mineralogical Magazine Signup for GSW Email News
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Mineralogical Magazine; December 1998; v. 62; no. 6; p. 869-876
This Article
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 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 Google Scholar
Google Scholar
Right arrow Articles by Massonne, H. J.
Right arrow Articles by Willner, A. P.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Zussmanite in ferruginous metasediments from Southern Central Chile

H. J. Massonne, F. Herve, O. Medenbach, V. Munoz, and A. P. Willner

Universitaet Stuttgart, Institut fuer Mineralogie und Kristallchemie, Stuttgart, Federal Republic of Germany

Zussmanite KFe 13 [AlSi 17 O 42 ](OH) 14 , a modulated 2:1 layer silicate, has so far been found only in ironrich metasediments from Laytonville. California (Agrell et al., 1965). A new occurrence is reported here from Punta Nihue north of Valdivia, Chile, in banded stilpnomelane-schists. These are intercalated in the "Western Series", a complex of low-grade metamorphic rocks with local high-pressure, low-temperature overprint (e.g. blueschists). The rock contains conspicuous porphyroblasts of zussmanite of mm size and is composed of chemically distinct bands with the subsequent assemblages: (1) zussmanite-stilpnomelane-quartz, (2) siderite-quartz+ or -stilpnomelane (3) apatite-stilpnomelane-quartz+ or -siderite. The chemical composition of zussmanite. (K (sub 0.80) Na (sub 0.05) Ba (sub 0.01) )(Fe (super 2+) (sub 11.29) Mg (sub 1.11) Mn (sub 0.25) Fe (super 3+) (sub 0.14) Cr (sub 0.01) Al (sub 0.19) Ti (sub 0.01) )[Al (sub 1.23) Si (sub 16.77) O (sub 4.2) ](OH) 14 , its optical properties and X-ray data correlate well with the Californian occurrence. Additionally, we present new IR data. In type (2) bands of fine-grained crystals of a K.Al poor mineral formed from siderite and quartz. Its chemical composition is close to that of zussmanite. A similar phase was also reported from Laytonville, California (Muir Wood, 1980). The rarity of rock-forming zussmanite can be explained by its occurrence in strongly Fe-rich and reduced rocks, as well as, by a possibly narrow P-T stability field.

This record provided courtesy of AGI/GeoRef.




This article has been cited by other articles:


Home page
 Can MineralHome page
A. P. Willner, S. Pawlig, H.-J. Massonne, and F. Herve
METAMORPHIC EVOLUTION OF SPESSARTINE QUARTZITES (COTICULES) IN THE HIGH-PRESSURE, LOW-TEMPERATURE COMPLEX AT BAHIA MANSA, COASTAL CORDILLERA OF SOUTH-CENTRAL CHILE
Can Mineral, December 1, 2001; 39(6): 1547 - 1569.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Mineralogical Society of Great Britain and Ireland