Arsenic, Stibarsen

The Engineer Mine is a gold-silver mine famous for the occurrence of native arsenic and stibarsen in the veins. Here is a good example of fresh, black, native arsenic interlayered with thin films of  the more metallic stibarsen.  This mine has been closed for a hundred years and not likely every to operate again. I did a collecting project there, a number of years ago and found only sparse amounts of stibarsen and native arsenic. This specimen shows convex botryoidal arsenic and stibarsen on the top and the same minerals as convex botryoids on the bottom!