Sphalerites from the Force Crag Pb-Zn vein, N England, show darker coloured zones found not only to be richer in Cu, Fe, Sb, Ag and Pb but also to contain precipitates of tetrahedrite-like composition. Sphalerites from Silvermines, Ireland, also showed trace-element enriched colour banding but were devoid of precipitates. A low-iron sphalerite from Tyndrum, Scotland, showed opaque bands found to be enriched in Cu and Fe related to the intergrowths of digenite. -R.A.H
