Twinned selenite (gypsum) crystals from the Willow Creek location, near Nanton, Alberta, Canada. These crystals show a very unique fluorescent response under UV light, producing a bright hourglass-shaped area of zonal fluorescence that is characteristic for selenite crystals from the Willow Creek location. This response is seen under both short and long wave UV. This specimen is also phosphorescent under both wavelengths, most brightly under short wave. 41 x 29 x 19 mm, 15 grams.