Lethbridge selenite crystals are fluorescent under ultraviolet light, exhibiting an “hourglass” pattern that is not visible in normal light. It is clearly visible in short-wave, medium-wave and long-wave ultraviolet, most prominent in short-wave. These crystals are also phosphorescent – the hourglass pattern remains briefly visible in a green hue in total darkness after the ultraviolet light source is extinguished – the selenite crystal then fades and then it too is dark.