Babingtonite and Fe-rich Ca-Al Silicates from Western Southland, New Zealand

M. B. Duggan*
Department of Geology, University of Otago, Dunedin, New Zealand
*Present address: Bureau of Mineral Resources, GPO Box 378, Canberra, ACT, 2601, Australia.

Abstract: Babingtonite is a common constituent of calcareous volcanic detritus in the interstices of pillow lavas from an outcrop of the Takitimu Group, western Southland, New Zealand, Associated minerals include Fe-rich prehnite (Fe/(Fe+Al) = 0.12–0.33), Fe-rich epidote (Ps24–53), grandite garnet (av. Andradite70 Grossular30), quartz, calcite, chlorite, and pumpellyite. Babingtonite shows little departure from its ideal composition other than minor Mg, Mn, and Al and a trace of Na.

Textural evidence and microprobe data suggest that the babingtonite, Fe-rich epidote, calcite, and quartz formed from hydrothermal solutions by direct precipitation in open cavities and by replacement of higher temperature silicate phases (in particular plagioclase and basaltic glass) in a shallow marine volcanic environment. During subsequent burial and low-grade metamorphism babingtonite was partially replaced by prehnite, less Fe-rich epidote, grandite, and chlorite.

Keywords: babingtonite • prehnite • epidote • garnet • chlorite • pumpellyite • Southland • New Zealand

Mineralogical Magazine; December 1986 v. 50; no. 358; p. 657-665; DOI: 10.1180/minmag.1986.050.358.11
© 1986, The Mineralogical Society
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