Colusite on Quartz (type locality)
East Colusa Mine, Butte, Silver Bow County, Montana, USA
Cabinet, 11.5 x 9.1 x 6.8 cm
Colusite is one of the most rare sulfides, and occurred at its best from this classic locale in the early to mid 1900's. Emplaced on a matrix composed mostly of massive, milky quartz is a large druse of lustrous, dark gray colusite: an uncommon, copper, vanadium, arsenic, tin, antimony sulfide. This specimen is from the type locality of the East Colusa Mine, Butte, Montana. It is huge, rich, and incredibly rare - in fact, it is more Colusite than I have seen on all other specimens, few as they are, put together. This came out of an old California collection. It has been checked by RAMAN at the University of Arizona.