An awesome specimen of iridescent Bornite coating octahedral Pyrite crystals to 1cm with micro crystals of Quartz. Look close at the photos, these are actually cubo-octahedral crystals. According to Jenkins & Lorengo (Min. Record v. 33, n. 1 2002), Pyrite is rather abundant at Butte but they also report octahedral crystals as rare in Main Stage veins. The Stewart is a Main stage Anaconda vein.