American Mineralogist, Volume 68, pages 100,1-1008, /983 Ilvaite, an alteration product replacing olivine in the Skaergaard intrusion

Ilvaite, CaFe?+Fe3+(OH)Si2Os, is an abundant mineral in the upper parr of the Skaergaard intrusion of East Greenland. It occurs in these rocks as an alteration product replacing fayalitic olivine. Analyses of unaltered olivine and ilvaite demonstrate that the replacement process requires the removal...

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Bibliographic Details
Main Authors: H. R. Nasrunn, J M. Huches, R. W. Brnnrb
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Subjects:
Greenland
East Greenland
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.520.5481
http://rruff.info/doclib/am/vol68/AM68_1004.pdf
Description
Summary:Ilvaite, CaFe?+Fe3+(OH)Si2Os, is an abundant mineral in the upper parr of the Skaergaard intrusion of East Greenland. It occurs in these rocks as an alteration product replacing fayalitic olivine. Analyses of unaltered olivine and ilvaite demonstrate that the replacement process requires the removal of FeO and MgO from the olivine and the addition of CaO, H2O, and 02. Single crystal X-ray diffraction studies indicate that the Skaergaard ilvaite is the orthorhombic polymorph. It is suggested that the ilvaite crystal-lized under conditions of high /Hzo, low.7co2, low /C2, and moderate? during the subsolidus cooling of the intrusion.

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