Very Phosphorescent Radiating Willemite, on Calcite - Franklin, New Jersey

Contributed by: Howie Green
Date: Mar 8th, 2026
Locality: Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)

Description:
As explained by Earl Verbeek, resident Franklin FLM guru: "The term "radiating willemite" has nothing to do with its fluorescent or phosphorescent properties and refers only to the radiating habit of the mineral. In tight fractures these can take the form of intergrown, flat, radiating rosettes, but in larger openings one can get three-dimensional radiating masses. The latter are locally referred to informally as "cones. " Most radiating willemite from Franklin and Sterling Hill shows bright and prolonged phosphorescence, but some does not where it has been serpentinized; these are usually tan to brown in color. There is also many local willemite that shows wonderful phosphorescence but does not have a radiating habit. "

Willemite = green, Calcite= red/org - Second pic shows the extreme phosphorescence....

Originally posted by Howie Green on Nature's Rainbows.

Fluorescence under shortwave UV light.

Afterglow after exposure to shortwave UV light.

Normal light.

Summary of luminescence responses:

Willemite (Mindat) (RRUFF)

• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Green
• Afterglow after exposure to Shortwave (254nm Lamp/Mercury) UV light: Green

• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Red