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; August 2003; v. 67; no. 4; p. 799-806; DOI: 10.1180/0026461036740136
© 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 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 Google Scholar
Google Scholar
Right arrow Articles by Choo, C. O.
Right arrow Articles by Kim, Y.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Textural and spectroscopic studies on hydrothermal dumortierite from an Al-rich clay deposit, southeastern Korea

C. O. Choo* and Y. Kim

Department of Geology, Kyungpook National University, Daegu, 702–701, Korea

* E-mail: chooco{at}hanmir.com

Dumortierite occurs as small nodules or thin layers along horizontal fractures in the altered volcanic rocks of the Milyang clay deposit, southeastern Korea. Textural evidence shows that dumortierite is associated with pyrophyllite, suggesting that the silica activity increased with decreasing B and Al activities during the hydrothermal alteration. Dumortierite chemistry shows a slight excess of Al, possibly due to common occurrence of Al-rich minerals in the clay deposit. The structural formula of dumortierite is recalculated as Al6.93(Fe0.03Mg0.07)B(Si2.99Al0.01)O18. An absorption peak at 1387 cm in the IR spectrum indicates that B is present in three-fold coordinated sites. The 29Si MAS NMR spectrum has two peaks at –90.9 and –95.5 ppm, showing that Si in dumortierite is located in two different crystallographic sites and is linked to four octahedral Al atoms. The 27Al MAS NMR spectrum shows only one asymmetrical peak near 0 ppm, suggesting that there is no substitution of Al for Si. The 11B MAS NMR spectrum at 17.5 ppm shows a typical second order quadrupole pattern represented by the three-fold coordinated B. The 11B chemical shifts indicate that all of the B occupies such sites, indicating that the B sites are axially symmetric or nearly so in a very well defined site.

KEYWORDS: dumortierite, clay deposit, boron, trigonal group, MAS NMR, Korea






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