Chlorophane, Sphalerite, Fluorapatite, Willemite - Franklin, New Jersey

Contributed by: Chris Clemens
Date: Apr 27th, 2026
Locality: Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)
Size: 27 x 19 x 41 mm

Description:
This is a beautiful 4-color, mixed mineral, fluorescent specimen from the Franklin Mine, Franklin, New Jersey. The primary component is chlorophane, an amber/brown colored variety of fluorite that shows a teal blue/green, fluorescent response and is thermoluminescent (emits light when heated). This rock also contains sphalerite, fluorapatite and willemite. Under shortwave UV the chlorophane fluoresces teal blue/green, sphalerite pink, fluorapatite orange, and willemite classic bright green. The chlorophane is also strongly phosphorescent after exposure to shortwave UV. Under midwave UV the chlorophane shows a similar, but dimmer teal response, while the sphalerite (pink) and fluorapatite (orange) both fluoresce more brightly. Under longwave UV the chlorophane again shows a dim, teal-colored response, and the sphalerite fluoresces a violet color. Very little of the orange fluorescing fluorapatite can be seen under longwave.

Originally posted by Chris Clemens on Nature's Rainbows in 2017.