For the sake of variety, this ugly thing is a sample of the rare copper sulfide anilite (Cu7S4), from the Champion Mine, in the lower portion of the Keweenaw Peninsula. The area is most famous for its coppers, silvers, and datolites, but there actually are a number of other minerals that occur there-- some quite rare. A few have even been discovered there-- it think about 6 or 7 (mostly copper bearing, go figure) between Houghton and Keweenaw Counties, which account for the bulk of the Keweenaw peninsula portion of the greater Upper Peninsula (it's a peninsula on [in?] a peninsula.... I was completely confused about this as well until the local hotel guy set me straight.)