Willemite Crystals from Franklin, New Jersey

Contributed by: Michael Crawford
Date: Jun 22nd, 2025
Locality: Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)
Size: 4.5 x 4.5 cm

Description:
A small specimen of clear and pale green willemite crystals on a fracture surface from the Franklin Mine, Franklin, New Jersey. The willemite fluoresces bright green under all wavelengths of UV illumination. The shortwave emission spectrum has a maximum of 521 nm.

Fluorescence under shortwave UV light.

Normal light.

Shortwave Emission Spectra

Summary of luminescence responses:

Willemite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Green
• Fluorescence under Midwave (305nm LED) UV light: Green
• Fluorescence under Shortwave (255nm LED) UV light: Green