Utah and Montana Paper - The Association of Minerals in the Gagnon Vein, Butte City, Montana.

WHILST most of the silver- and copper-bearing veins of Butte have characters somewhat similar, the Gagnon vein has certain rather remarkable features which are not noticed in any of the other mines. The silver-veins proper, as illustrated in the Alice, Lexington, Moulton, and many others, have certain well-known typical characters. Manganese is always present in variable quantities as rhodocrosite or rhodonite, associated with quartz, pyrite, and sphalerite, and with little or no copper. The copper-veins also have certain mineralogical characteristics, which are very similar, or different only in minor points. Chalcocite, chalcopyrite, bornite, enargite, with variable quantities of pyrite, may be said to represent the general mineralogical features of these lodes. It is worth noticing that while the silver-bearing lodes have more or less sphalerite, this mineral is almost entirely