A curious crystal from the Binn Valley, Switzerland

Abstract

Among the specimens that were presented to the British Museum by Dr. C. T. Trechmann in 1917 from the collection of his father, the late C. O. Treehmann, was a loose crystal~ which at first sight appeared to belong to one of the lead-grey species so long associated with the Binn Valley, but measurements made on the three-circle goniometer in the British Museum did not accord with the angles recorded for any of the species hitherto described. The crystal was recently submitted to a careful examination, but still the bi-angular co-ordinates of the faces differ from those given for any other species, and the only conclusion that can be drawn is that the crystal represents a new mineral species, and one peculiar to the Binn Valley.