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Sphalerite, Chlorophane, Apatite and Willemite from Franklin, New Jersey

This is a spectacular 4-color, mixed mineral, fluorescent specimen from the Franklin Mine, Franklin, New Jersey. This rock contains sphalerite, chlorophane, apatite and willemite. Depending on the UV wavelength of excitation, this piece shows a colorful variety of fluorescent responses. Some of the minerals are also strongly phosphorescent after exposure to UV. The size of this specimen is 96 x 74 x 54 mm, and it weighs 504 grams.

Shown in the above photograph under short wave UV (254 nm), the willemite fluoresces green, the apatite orange, the chlorophane teal blue, and the sphalerite shows a pink response.

Under mid wave UV (302 nm), the bright orange fluorescence of the apatite dominates the response, while the chlorophane glows blue and the sphalerite pink.

The above photograph shows the fluorescent response under long wave UV (365 nm). The chlorophane fluoresces blue/purple and the sphalerite shows a bright pink fluorescent response.

As is the case with many fluorescent rocks, this specimen is not too impressive looking under visible light.

The photo montage above illustrates the wavelength-dependent, variable color fluorescent response of this specimen.

As shown in the gallery of images above, this specimen is brightly fluorescent and phosphorescent under all UV wavelengths. The upper row shows fluorescence (left) and phosphorescence (right) under short wave UV. The middle row shows the same under mid wave UV, and the lower row shows the long wave UV responses. Click on the individual images for a larger view.

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