Canadian Rockhound: The Society Girl Mine

The Society Girl Mine, which is located in the East Kootenays in southeastern British Columbia, is renown for the fine pyromorphite specimens which it has produced. Pyromorphite, a lead chlorophosphate, occurs as a secondary mineral in the oxidized zones of lead bearing veins. Such occurrences are quite rare in Canada, which makes this mine all the more noteworthy.

Pyromorphite, Society Girl Mine, British Columbia, Canada. Miniature specimen from the collection of Tony Smith. View large image.

In the Annual Report of the Minister of Mines (B.C.) for the year 1909, mention is made of the Society Girl group which consisted of seven Crown-granted claims located about two miles southeast of the town of Moyie. It is just over the crest of the first range of hills east of Moyie Lake about 2000 feet above the lake. The ore was primarily galena, carrying about 1/2 ounce of silver to the percent of lead. It occurs in a quartz gangue associated with some zinc. In the surface workings, the galena was heavily oxidized so that the ore which was mined was primarily lead carbonate (cerrusite) with some galena. Mention is also made of "some very pretty crystals of pyromorphite".

The occurrence is also discussed in the Geological Survey Memoir #76 (1915). The formation is described as the oldest subdivision of the Purcell series called the Aldridge formation, which here strikes north-south with a dip of 25 degrees to the east. The vein strikes N. 60 degrees W. with a dip of 60 degrees to the south and appears to be in the great zone of fissuring which traverses the Moyie area. The vein is narrow where it traverses thin-bedded argillaceous quartzites and widens out in the heavier-bedded quartzites. Mention is also made of the oxidized zone which is exposed in the upper workings consisting of cerrusite and pyromorphite which occurs both in massive forms and beautiful crystals. The cerrusite is white to colourless and occurs in tabular crystals, either singly or as penetration twins. It is often embedded in dense masses of limonite.

The pyromorphites generally occur as yellow green to green prismatic crystals, some of which have a somewhat curved or "barrel-shaped" appearance. Single crystals up to one inch and larger crystal aggregates have been noted. These, evidently, were fairly loosely attached to the matrix which, perhaps, allowed many of them to escape being shipped to the smelter. Much less common are clusters or groups of prismatic crystals on matrix. Clusters exceeding two or three inches can command quite good prices today. Originally, these may have been more common, but, because the ore was hand sorted, many of them may have been sent to the smelter.

In the summer of 1975, the site was mined for specimens by Rod Tyson (Tyson's Fine Minerals) and John Gorham. They met with modest success and were able to recover several flats of specimens as well as innumerable thumbnails. Returning the following summer to try their luck again, they met with a somewhat different result and were only able to obtain a small number of thumbnails.

One example of a specimen from their 1975 efforts is shown here. It currently resides in the author's collection. It measures approximately 2 by 1.5 by 1 inch. The crystals are yellow green in colour and are up to 0.5 inch long.

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The preceding article was first published in the May 1999 issue of the Mineral Vein, the official newsletter of the Mineral Society of Manitoba. Reprinted in the Canadian Rockhound with permission from the author.