Mixture of wurtzite and sphalerite from: Horn Silver Mine, Frisco, San Francisco District, San Francisco Mts, Beaver Co., Utah, USA.
When Don Newsome visited me in 2002 he gave me this specimen as a door prize. It's very strongly triboluminescent ! (you can see the scratchmarks.)
The orange fluorescence is probably wurtzite, the violet stuff sphalerite. Photo in SW-UV.
