Glow Stick Barite - Linwood Mine, Buffalo, Iowa
Contributed by: Chris Clemens
minID: 4PA-C6D
Date: May 21st, 2026
Locality: Linwood Mine, Buffalo, Scott County, Iowa, USA (See on Mindat)
Size: 11.2 x 2.3 x 14.2 cm
Weight: 151 g
Description:
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 County, Iowa, the Linwood Mine is one of the largest underground limestone mines currently in operation in the United States.
Glow stick barite shows bright blue/white fluorescence under longwave UV (365 nm). Interestingly, 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 longwave UV (365 nm). The shortwave response is similar to that seen under longwave UV, but less bright. Pale blue/green phosphorescence/afterglow is seen following exposure to shortwave UV (254 nm).
Mindat.org Photo of the Day - 1st May 2021
Originally posted by Chris Clemens on Nature's Rainbows in 2020.
Summary of luminescence responses:
Baryte (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm Lamp/Mercury) UV light: White
- Afterglow after exposure to Longwave (365nm Lamp/Mercury) UV light: Green
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: White
- Afterglow after exposure to Shortwave (254nm Lamp/Mercury) UV light: Blue