Brightly fluorescent andersonite with a minor metamunirite druse, from the D Day #2 Mine, Yellow Cat District, Grand County, Utah. Andersonite is a rare secondary uranium carbonate mineral that forms as small bright to dull yellowish green colored translucent rhombohedral crystals, and as fine-grained drusy crystal aggregates. Being a uranium-containing mineral, andersonite is radioactive and is brightly fluorescent, showing a brilliant blue/green response under both short wave and long wave UV, brightest under short wave. The radioactivity of this specimen is approximately 1800 cpm at 1 cm. Size is 4.3 x 3.8 x 1.3 cm.
Brilliant blue/green fluorescence is seen under short wave UV (254 nm).
Bright blue/green fluorescence under long wave UV (365 nm).
The specimen shown under visible light. The andersonite is the pale yellow/green colored mineral.