This specimen, from Franklin, New Jersey, is of mixed composition and contains brick-red willemite (troostite), white and greenish/white willemite, white calcite, and black grains of franklinite. Under short wave UV the troostite and willemite fluoresce bright green and the calcite shows a typical red response. The white willemite is also phosphorescent. The size of this specimen is 54 x 52 x 51 mm, and it weighs 174 grams.
Under short wave UV (254 nm), the willemite shows bright green fluorescence and the calcite shows a red response.
Same view under visible light. Note the various colors of willemite- white, apple green and the brick red troostite.
Reverse side of same specimen, shown under short wave UV (left) and visible light (right). Click on the images above for a larger view.