Novacekite from Mexico
Contributed by: Michael Crawford
Date: Jul 26th, 2025
Locality: Cuervo Mine, Sierra Gomez, Aldama Municipality, Chihuahua, Mexico (See on Mindat)
Size: 8 x 11 cm
Description:
A specimen of novacekite (Mg(UO2)2(AsO4)2 · 10H2O) from the Cuervo Mine, Chihuahua, Mexico. The uranyl ion is part of novacekite’s crystalline structure. Therefore, the yellow green fluorescence of novacekite is intrinsic. The novacekite occurs as inclusions in aragonite crystals. The yellow green fluorescence is equally bright under all UV wavelengths.
The emission spectrum of novacekite has three peaks at 505 nm, 524 nm, and 545 nm. The spectral signature of novacekite is different from several other uranium minerals that also have yellow green fluorescence.
The radioactivity of this specimen is around 1400 CPM. It is higher because the uranyl ion is part of the mineral structure and not a trace amount replacing some element in a mineral.
Summary of luminescence responses:
Novacekite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm Lamp/Mercury) UV light: Green
- Fluorescence under Midwave (305nm LED) UV light: Green
- Fluorescence under Shortwave (255nm LED) UV light: Green