Adamite on Limonite from the Ojuela Mine
Contributed by: Douglas Bank
minID: 0TN-2A7
Date: May 1st, 2026
Locality: Ojuela Mine, Mapimí, Mapimí Municipality, Durango, Mexico (See on Mindat)
Size: 3.5 x 1.2 x 5 cm
Description:
This specimen consists of adamite crystals on a limonitic matrix from the Ojuela Mine. In daylight, the adamite appears as numerous transparent to translucent crystals with a pale yellowish-green hue. The crystals are generally small and closely packed, which, combined with their clarity, can make individual forms difficult to distinguish under normal lighting conditions.
Under shortwave ultraviolet light, the specimen transforms dramatically. The adamite fluoresces a vivid green, and the crystals become optically opaque, revealing a complex, interlocking pattern of crystal aggregates of varying sizes. This fluorescence is characteristic of adamite and is commonly attributed to trace amounts of uranium substituting into the crystal structure. The resulting contrast highlights internal zoning and structure that are not readily visible in white light.
The accompanying images were captured separately under white light (flash) and shortwave UV illumination, then digitally aligned to allow direct comparison of the same crystal features under different lighting conditions.
Summary of luminescence responses:
Adamite (Mindat) (RRUFF)
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Green