Esperite, Willemite, Calcite, Hardystonite

Contributed by: Howie Green
Date: Mar 9th, 2026
Locality: Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)

Description:
Classic 4-color from Franklin, New Jersey - the fluorescent mineral capital of the world.

Originally posted by Howie Green on Nature's Rainbows.

Fluorescence under shortwave UV light.

Summary of luminescence responses:

Calcite (Mindat) (RRUFF)

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

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

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

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