Selenite with "Hourglass" Fluorescence from Alberta, Canada

Contributed by: FMS Admin
Date: May 14th, 2026
Locality: Willow Creek, Nanton, Alberta, Canada (See on Mindat)
Size: 2.2 x 1.7 x 4.6 cm

Description:
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 minor abrasion damage on one edge, the specimen is in good overall 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 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.

Originally posted by Frédéric Messier Leroux on Nature's Rainbows in 2021.

Fluorescence under shortwave UV light.

Afterglow after exposure to shortwave UV light.

Normal light.

Summary of luminescence responses:

Gypsum var. Selenite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Blue
• Fluorescence under Midwave (305nm LED) UV light: Blue
• Fluorescence under Shortwave (255nm LED) UV light: Blue
• Afterglow after exposure to Shortwave (255nm LED) UV light: Blue