Adamite from the Ojeula Mine, Durango, Mexico
Contributed by: Michael Crawford
Date: Jul 12th, 2025
Locality: Ojuela Mine, Mapimí, Mapimí Municipality, Durango, Mexico (See on Mindat)
Size: 6 x 8 cm
Description:
An adamite (Zn2(AsO4)(OH)) specimen from the Ojeula Mine, Mapimi, Durango, Mexico. Adamite is a secondary mineral found in zinc deposits that contain arsenic bearing minerals. There is also uranium in the deposit that is dissolved along with zinc and arsenic and is precipitated to form adamite. The hexavalent uranium as uranyl ions activates the green fluorescence in adamite. The green fluorescence is bright under all UV wavelengths. The longwave and shortwave emission spectra are the same. The spectra have sharp vibronic peaks at 509 nm, 528 nm, and 550 nm characteristic of the response from the linear uranyl ion.
The adamite has slight radioactivity (110 CPM) due to the presence of uranium.
Summary of luminescence responses:
Adamite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Green
- Fluorescence under Midwave (305nm LED) UV light: Green
- Fluorescence under Shortwave (255nm LED) UV light: Green