Lustrous root beer-colored fluorite cubes on a light grey limestone matrix, from the Stoneco White Rock Quarry, Clay Center, Ottawa Co., Ohio. Fluorite specimens from Clay Center, Ohio, are notable for their bright white, zoned fluorescence under long wave UV. Also impressive under short wave UV, the fluorite shows a cooler white, and slightly dimmer fluorescent response. This material is also phosphorescent under both wavelengths, showing a white glow after short wave UV, and green after long wave. The fluorescence in the Clay Center fluorites is likely due to the presence of an organic activator. The size of this specimen is 83 x 58 x 35 mm, and it weighs 166 grams.
The Clay Center quarry location has been closed to collecting for years, but fine specimens of this material can still be found in old collections and at shows.
The above photograph shows the specimen under visible light.
Fluorescence under long wave UV (365nm).
Close-up detail of the long wave UV response showing fluorescent zoning within the fluorite cubes.
Green phosphorescence following exposure to long wave UV.
Fluorescence under short wave UV (254nm).
Pale phosphorescent response following exposure to short wave UV.