This specimen is from a find made at the Linwood Mine, in Buffalo, Iowa, in September 2020, and consists of flat, prismatic, pale yellow/tan barite crystals on a light grey siltstone matrix. The barite shows bright blue/white fluorescence under all UV wavelengths with strong phosphorescence/afterglow. The large pocket that produced this specimen was appropriately nicknamed the "Glow Stick Pocket" by mineral dealer Everett Harrington, who distributed many of the specimens from this find.
Located on the banks of the Mississippi River in Buffalo, Scott Co., Iowa, the Linwood Mine is one of the largest underground limestone mines currently in operation in the United States.
Glow stick barite showing bright blue/white fluorescence under long wave UV (365 nm). Interestingly, the fluorescence is constrained to the surfaces of the crystal faces, and occurs preferentially on surfaces that have a distinct frosted/etched appearance.
Short-lived, but bright green phosphorescence/afterglow is seen following exposure to long wave UV (365 nm).
Same specimen shown under short wave UV (254 nm). The short wave response is similar to that seen under long wave UV, but less bright.
Pale blue/green phosphorescence/afterglow is seen following exposure to short wave UV (254 nm).
Same specimen shown under visible light. This piece measures 14.2 x 11.2 x 2.3 cm and weighs 151 grams.