Hutchinsonite,

Brilliant crystals of the thallium mineral, hutchinsonite cover the top of this large plate. The matrix is composed of sphalerite, pyrite and quartz. There is some green tinting which belies the presence of, probably chalcopyrite. The hutchinsonite crystals are very sharp, terminated and often in curved/divergent crystals or groups of crystals. Good looking hutchinsonite specimen!