This is an exceptionally bright fluorescent adamite specimen from the Ojuela Mine, Mapimi, Durango, Mexico. Under visible light, yellow/green adamite crystals are seen on a contrasting red/brown gossan matrix. This specimen is brightly fluorescent under both short and long wave UV, with the short wave fluorescence rivaling some of the Franklin willemites. The size of this piece is 48 x 40 x 23 mm.
Adamite is a secondary zinc arsenate hydroxide found in zinc ore deposits containing arsenic-bearing minerals.
The above image shows bright green fluorescence under short wave UV (254 nm).
A similar green, but less bright, fluorescent response is seen under long wave UV (365 nm).
Same specimen shown under visible light.