To mineral collectors, the Sweet Home Mine in Alma, Colorado is best known as a producer of some of the finest rhodochrosite specimens in the world. During the process of trimming these rhodochrosites to remove excess matrix, waste material is produced which sometimes contains fluorescent sphalerite and fluorite, both of which show a bright two-color response under long wave UV. The specimen featured here is an excellent example of such material and contains a combination of brightly fluorescent sphalerite and fluorite, and minor amounts of non-fluorescent pyrite and rhodochrosite. The size of this piece is 62 x 53 x 30 mm, and it weighs 137 grams.
In the photograph above, taken under long wave UV (365nm), the sphalerite shows bright orange fluorescence and the fluorite shows a blue/purple response.
Under short wave UV (254nm), a similar, but dimmer and more pale fluorescent response is seen.
Same specimen shown under visible light. Note the brassy-colored pyrite.