This is a classic specimen of "Christmas Calcite" from the Sterling Mine, Sterling Hill, Ogdensburg, New Jersey. This material contains brightly fluorescent willemite and calcite, with non-fluorescent franklinite and zincite. Under short wave UV, the willemite shows a bright green response and the calcite fluoresces bright red. Perfect for getting you into the holiday spirit! This specimen shows an interesting multi-wave response, as it is also fluorescent under long wave UV, with the willemite showing a more subdued green fluorescence, and the calcite glows magenta/pink. The size of this piece is 7.6 x 7.6 x 3.8 cm, and it weighs 428 grams.
Under short wave UV (254 nm) this rock has a very festive look. Willemite glows bright green and calcite fluoresces bright red. The black, non-fluorescent grains are franklinite.
The long wave UV (365 nm) response is less bright, but still quite colorful. The willemite response is more blue/green and the calcite shifts to pink/magenta.
Same rock shown under visible light. The calcite is white, willemite brown and franklinite black.