Plumbogummite ps. after Pyromorphite, Yangshuo Mine, China
This is a large specimen consisting of pale sky-blue plumbogummite psuedomorph that has replaced an intergrown cluster of hexagonal pyromorphite prisms, from the Yangshuo Mine, Yangshuo Co., Guilin Prefecture, Guangxi Ahuang Autonomous Region, China. Little to no matrix is present. Some residual yellow-green unaltered pyromorphite can still be seen at the ends of some of the crystals. The plumbogummite fluoresces under all UV wavelengths, but is best under mid wave UV. The size of this specimen is 16.3 x 14.5 x 7.9 cm and it weighs 652 grams.
Note: Although these Chinese plumbogummite psuedomorphs are usually attributed to the Yangshuo Mine, a new report published by Wilson and Moore in the Nov-Dec, 2022 issue of The Mineralogical Record (The Laohuan Mine, pp 697-732) indicates that this locality information is incorrect and that the true location is the Laohuan Mine, which is located approximately 10 km to the north.
The above photo shows fluorescence under mid wave UV (302 nm). The plumbogummite shows a bright green response while bright orange accents are provided by residual unaltered pyromorphite.
Under short wave UV (254 nm), the plumbogummite fluoresces green and the unaltered pyromorphite shows a burnt orange response. The green fluorescence is likely activated by uranyl (UO2+2) as evidenced by the radioactivity emitted by this specimen (approx. 200 cpm / 10x background).
Bright, monochromatic, pale blue fluorescence is seen under long wave UV (365 nm).
Same specimen shown under visible light. Note the residual yellow-green unaltered pyromorphite, seen mainly at some of the crystal tips.