Multi-Colored Sphalerite, Balmat No. 4 Mine, Balmat, New York

Contributed by: Chris Clemens
minID: EFX-LVU
Date: Apr 16th, 2026
Locality: Empire State No. 4 Mine, Balmat, Fowler, St. Lawrence County, New York, USA (See on Mindat)
Size: 6.8 x 4.3 x 11.6 cm
Weight: 457 g

Description:
Oblong piece of fluorescent sphalerite from the ZCA Mine No. 4 (now called the Empire State No. 4 Mine), Balmat, St. Lawrence Co., New York. When viewed under visible light, this material is not particularly attractive, being a metallic grey colored rock and gives no indication of its beautiful multi-colored fluorescent response under UV. No two specimens of this material are the same, as each shows a unique, multi-colored, pattern of fluorescence. These specimens typically show their brightest fluorescent response under longwave UV. This material typically shows phosphorescence (afterglow) following exposure to UV.

This material is sometimes referred to as "birdseye sphalerite" or "birdseye ore" due to the pattern of its multi-colored fluorescence.

Originally posted by Chris Clemens on Nature's Rainbows in 2023.

Fluorescence under longwave UV light.

Afterglow after exposure to longwave UV light.

Fluorescence under shortwave UV light.

Afterglow after exposure to shortwave UV light.

Normal light.

Summary of luminescence responses:

Sphalerite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Orange
• Fluorescence under Longwave (365nm LED) UV light: Green
• Afterglow after exposure to Longwave (365nm LED) UV light: Orange
• Afterglow after exposure to Longwave (365nm LED) UV light: Green