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

Contributed by: Chris Clemens
minID: JD0-TH9
Date: Apr 19th, 2026
Locality: Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)
Size: 74 x 54 x 96 mm
Weight: 504 g

Description:
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. This specimen is not too impressive looking under visible light, but 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 willemite fluoresces green, the apatite orange, the chlorophane teal blue, and the sphalerite shows a pink response under short wave UV (254 nm). Bright orange fluorescence of the apatite dominates the response under mid wave UV (305 nm), while the chlorophane glows blue and the sphalerite pink. Under long wave UV (365 nm), the chlorophane fluoresces blue/purple and the sphalerite shows a bright pink, fluorescent response.

Originally posted by Chris Clemens on Nature's Rainbows in 2020.