Here is a nice floater crystal of gypsum var. selenite, from Willow Creek, near Nanton, Alberta, Canada, showing the typical "hourglass" zoned fluorescence that these crystals are famous for. Apart from some pretty minor abrasion damage on one edge, the specimen is in overall good shape, and fluoresces nicely under all three UV wavelengths. Second-generation crystallization is attached on one side of the crystal.
Under longwave, midwave and shortwave, the color of the fluorescence is the same, and the intensity of the fluorescence is pretty similar too. Therefore, only the SW response is shown, along with the SW phosphorescence. The specimen is shown in white light in the last picture.
Size: 4,6 cm X 2,2 cm X 1,7 cm
Shortwave UV fluorescence
SW UV phosphorescence/"afterglow/