Sphalerite - Horn Silver Mine, Frisco, Utah
Contributed by: Chris Clemens
minID: 1FG-5VR
Date: May 2nd, 2026
Locality: Horn Silver Mine, Frisco, San Francisco Mining District, Beaver County, Utah, USA (See on Mindat)
Size: 47.6 x 39 x 63.7 mm
Weight: 114 g
Description:
The Horn Silver Mine is located in the town of Frisco, Beaver County, Utah, and during its heyday in the late 1870s, was one of the richest silver producing mines in the world. This location is notable to fluorescent mineral collectors because it has also produced some of the most unique fluorescent sphalerite known. The sphalerite of the Horn Silver Mine is brightly fluorescent and often responds to UV in a multitude of colors including orange, pink, red, blue, green, yellow, teal and others! This material also shows bright and lasting phosphorescence. It also displays the property of triboluminescence, emitting orange flashes of light when scratched with a sharp object.
This is a classic example of fluorescent sphalerite from the Horn Silver Mine. It contains grains of fluorescent sphalerite in a non-fluorescent limestone breccia. The brightest fluorescence/phosphorescence is seen under longwave UV.
Originally posted by Chris Clemens on Nature's Rainbows in 2018.
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