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On the genesis and composition of natural pyroaurite

Published online by Cambridge University Press:  09 July 2018

R. M. Taylor ,
H. C. B. Hansen ,
G. Stanger  and
C. Bender Koch
R. M. Taylor
Affiliation:
CSIRO Division of Soils, Private Bag 2, Glen Osmond, South Australia
H. C. B. Hansen
Affiliation:
Royal Veterinary and Agricultural University, Chemistry Department, Thorvaldsensvej 40, 1871 Frederiksberg, Copenhagen, Denmark
G. Stanger
Affiliation:
School of Earth Sciences, Flinders University, Bedford Park, South Australia
C. Bender Koch
Affiliation:
Laboratory of Applied Physics, Technical University of Denmark, Building 307, DK-2800 Lyngby, Denmark
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Abstract

Samples of the mineral pyroaurite, formed from the weathering of partially serpentinised harzburgite (olivine + pyroxene) were found in an arid region of the Sultanate of Oman. These were either golden or silver in colour depending on the horizon from which they were derived. Chemical analysis showed that the colour variation was primarily due to the differing conditions in the hydrological environment. The golden colour was attributed to small Fe(III) oxide particles detected by Mössbauer spectroscopy. In addition, the samples were examined by X-ray diffraction, scanning electron microscopy, and glycerol intercalation. These results were compared with a synthetic pyroaurite sample prepared under conditions (previously reported) similar to those in nature. These conditions are shown to approximate to those found in the hydrological environment in the zones of the natural pyroaurite formation.

Type
Research Article
Information
Clay Minerals , Volume 26 , Issue 3 , September 1991 , pp. 297 - 309
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1991

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