Here’s one for the connoisseur of rare fluorescent mineral species. Pollucite, a cesium-containing zeolite, isn’t particularly rare in itself, but fluorescence in pollucite is quite uncommon. This specimen shows pale yellow fluorescence under short- and mid-wave UV and was collected in 2019 by Mark Jacobson, current president of the Friends of Mineralogy, from the Valor Lithium and Cesium Pegmatite occurrence in Quebec, Canada. Interestingly, little to no fluorescence is produced under long wave UV. The size of this piece is 94 x 56 x 25 mm and it weighs 102 grams.
Pollucite is mined as a commercial source for the element cesium.
As shown in the photograph above, this pollucite specimens shows pale yellow fluorescence under short wave UV (254 nm).
Under mid wave UV (302 nm), a similar pale yellow fluorescent response is seen.
Under visible light, this pollucite specimen has a white to purple-pink color, and is composed of small intergrown crystal plates.