The state of Oklahoma is not known to be a prolific source of fluorescent mineral specimens. However, the Great Salt Plains, located in the town of Jet, in Alfalfa County, is famous for producing these well-formed, double terminated selenite crystals that show moderate fluorescence and phosphorescence under UV. Also known as gypsum, these crystals are unique because they typically contain hourglass-shaped inclusions of brown colored sand. Under UV they show a similar warm tan and pale blue fluorescence under both short and long wave, with blue/green phosphorescence after short wave and green after long wave UV. The largest crystal shown here measures 57 x 24 x 11 mm.
Bladed crystals of fluorescent selenite from the Great Salt Plains, Jet, Oklahoma, seen under short wave UV (254nm).
Same specimens seen under visible light. The larger crystal in the upper part of the photograph is approximately 57 mm in length. The brown-colored sand inclusions are clearly visible in both crystals.
The Great Salt Plains are located in northern Oklahoma, in Great Salt Plains State Park. Collecting these crystals is allowed seasonally from April 1st through October 15th annually. The following gallery shows the fluorescent and phosphorescent response of these interesting crystals under short and long wave UV.
Fluorescent (left) and phosphorescent (right) responses under short wave UV (upper) and long wave UV (lower). Click on the above images for a larger view.