Thometzekite (w. anglesite)

anglesite; galena

A vug in galena-rich sulphide ore hosts blocky crystals of colourless anglesite (to 7 mm) with etched faces. Both the anglesite and the sulphide are partly encrusted with pale green thometzekite which, under magnification, is made up of rosette-like aggregates of tabular, colour-zoned microcrystals each comprising a lime-green core with a very pale green surround.

Mark Feinglos acquired the specimen – labelled as helmutwinklerite – from John Metteer (The Mineral Mailbox) in 1984. A re-examination by Andy Roberts at the Geological Survey of Canada in 1998 confirmed that the pale green mineral is thometzekite.