Red fluorescence in fluorite is uncommon and is a response that is typically brightest under long wave UV (365 nm). Two notable locations are known to produce red fluorescent fluorite; Mapimi, Mexico and Berbes, Spain. Red fluorescence has also been reported in rare specimens from Cave-In-Rock, Illinois and England. Although the mechanism of red fluorescence in not known with certainty, it has been suggested that it may be activated by an interplay between rare earth elements and oxygen.
The specimen shown here is an outstanding example of red fluorescence in fluorite, and consists of a cluster of light purple fluorite cubes from the Taourirt Complex, Taourirt Province, Oriental Region, Morocco. As is the case with many of these red fluorescent fluorites, the red long wave response bleaches (fades) very rapidly, so fast in fact, that you can actually see it becoming dimmer before your eyes. The red response can be brought back by "recharging" the specimen under short wave UV (254 nm). As shown below, this is also a very attractive specimen under visible light. This piece measures 66 x 55 x 45 mm and weighs 147 grams.
Red fluorescent fluorite from the Taourirt Complex, Taourirt Province, Oriental Region, Morocco. Shown in the above photograph under long wave UV.
The same specimen shown under visible light.