Chlorophane from Franklin, New Jersey
Contributed by: Michael Crawford
Date: Aug 9th, 2025
Locality: Taylor Road dumps, Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)
Size: 7 x 9 cm
Description:
Fluorite var. chlorophane from the Taylor Road Dump, Franklin, Sussex County, New Jersey. The specimen also contains fluorescent sphalerite and fluorescent fluorapatite. These minerals are in a matrix of non-fluorescent pyroxene. The chlorophane from the Franklin area is also thermoluminescent and its fluorescence fades with prolong exposure to UV light and prolong exposure to sunlight. It should be stored in the dark to keep its fluorescence.
Chlorophane is unusual because of its blue-green fluorescence under midwave and shortwave UV light. It is also unusual for its green afterglow.
The fluorapatite grains in the specimen fluoresce orange and sphalerite fluoresces pink and blue under shortwave UV light. The sphalerite has orange afterglow when the shortwave light is turned off.
The shortwave spectrum is very noisy because the fluorescence is not very intense. However, the sharp peak at 312 nm in the ultraviolet region is real. Similar peaks around 310 nm occur in yttrofluorite specimens from New Mexico and Norway and chlorophane type fluorite specimens from Pakistan.
Summary of luminescence responses:
Fluorite var. Chlorophane (Mindat) (RRUFF)
- Fluorescence under Shortwave (255nm LED) UV light: Green
- Afterglow after exposure to Shortwave (255nm LED) UV light: Green