Canadian Rockhound: Clinozoisite

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Clinozoisite
By Richard Gunter, Winnipeg, MB, Canada

Clinozoisite, Ca₂Al₃(SiO₄)₃OH, is one of the more rare members of the epidote group of minerals. It generally occurs under metamorphic conditions where iron is lacking or tied up in other phases. The occurrence of clinozoisite prisms in galena at the Photo Lake mine near Snow Lake is a case in point, any iron in that system would have been tied up in the sulphides. The calcium, aluminum and silica would be free to form clinozoisite rather than the more common epidote.
Clinozoisite is typically found as a fine-grained replacement of feldspar and only rarely do the crystals grow to a macroscopic size. It has never been found in exceptional large crystals like its cousins epidote (e.g. Austria and Prince of Wales Island, Alaska) or zoisite (e.g. tanzanite from Tanzania). The best specimens are very similar to those from Photo Lake where it occurs in Long Prismatic Crystals up to 10 cm long and 5 mm wide, either as sheafs of parallel crystals in galena or as scattered single crystals in quartz. The crystals are light green-yellow, translucent, deeply striated and have a vitreous luster.

Copyright ©1997 Richard Gunter
E-mail: pamrichg@mb.sympatico.ca
This article may not be copied, distributed or reprinted in any form without the author's permission. To contact the author, please use the e-mail address provided. If you are unable to contact the author, please contact the Canadian Rockhound. Authorized reprints must acknowledge the author, original source and the Canadian Rockhound, and include the website URL address of the Canadian Rockhound.
The preceding article was first published in the January 1997 issue of the Mineral Society of Manitoba Newsletter. Reprinted in the Canadian Rockhound with permission.

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Document Number: win97_clinozoisite