Calcite, with strong "brief intense phosphorescence" - Estrie, Quebec, Canada
This calcite specimen, with the typical red fluorescence (best MW, then SW, then LW, as it's often the case with red fluorescing calcites), is not quite exceptionnal. But I still thought it was worth showing, first because fluorescent calcites from the Estrie region (formerly "Eastern Townships") are not often shown online, but also because it has a stronger than usual "brief intense phosphorescence" upon exposure to longwave.
I remain vague on the locale because the occurrence where this specimen was found was discovered by a friend of mine, who asked me not to disclose it.
Size: 7,7 cm X 6,7 cm X 2,7 cm
Shown respectively in the slideshow: SW UV, MW UV and LW UV fluorescence, LW UV "Brief intense phosphorescence", Visible light.