Tetradymite is an uncommon bismuth, tellurium sulfosalt, and this exceptional specimen for the rare species is from the venerable old mining area at Caldbeck Fells in Cumbria. This choice single crystal is a full 1.5 cm long, as exposed, and it has a bright, silvery, metallic luster. The provenance is outstanding, with old labels from Ward's, Larner Peak, and a Francis Butler label with Brompton Rd. address (that dates it between 1887 and 1927 for that collection). A classic Kay Robertson piece for both history and quality. This surely dates back to the early to mid 1800's heyday in this district, for specimen collecting. It is, so far as we know, generally considered the best locality for this very rare species.