A large, well-formed, red/brown willemite crystal sits on top of a matrix of white calcite, from the Sterling Mine, Sterling Hill, Ogdensburg, New Jersey. This specimen measures 86 x 76 x 48 mm, and weighs 405 grams.
The photograph above shows the fluorescent response under short wave UV (254 nm). The willemite fluoresces bright green and the calcite matrix shows a bright red/orange response.
As seen above, this specimen is also moderately fluorescent under long wave UV (365 nm). The willemite shows a more subdued green response and the calcite fluoresces a magenta color.
Visible light image of the same specimen.