Several well-formed, terminated, amber barite crystals on a dark chocolate brown matrix, from the Elk Creek area of Meade County, South Dakota. Under both short and long wave UV the barite fluoresces a honey white color, and phosphoresces blue/green after short wave and green after long wave. The Elk Creek area is notable for producing golden-amber colored barite crystals that are fluorescent under all UV wavelengths. The primary occurrence of this material is located along the bank of Elk Creek in the Black Hills of Western South Dakota, where the barite crystals have formed within the hollow interiors of calcareous concretions found in the surrounding Cretaceous age shale. The size of this specimen is 86 x 64 x 52 mm, and it weighs 273 grams.
Close-up of two of the barite crystals showing fluorescent response under short wave UV (254nm).
Additional images of the same specimen:
Click on the images above for a larger view and UV wavelength information.