Sphalerite from Horn Silver Mine, Utah
Contributed by: Douglas Bank
minID: C4P-8X6
Date: May 1st, 2026
Locality: Horn Silver Mine, Frisco, San Francisco Mining District, Beaver County, Utah, USA (See on Mindat)
Size: 3.7 x 4.5 x 4.6 cm
Weight: 127 g
Description:
This is a small, but exceptional specimen from the Horn Silver Mine. It is almost pure sphalerite in places, and glows brightly orange under LW UV (and also glows under all other wavelength tested, but not as brightly). It also glows blue and green in places where the sphalerite is a little less pure and there are other elements present such as barium and lead. The orange fluorescing sphalerite has an orange afterglow while the blue and green fluorescent stuff has a green afterglow.
This specimen also exhibits triboluminescence. If you scratch it, it seems like it creates orange sparks. It may also be thermoluminescent. If I shine an IR flashlight at it, it glows faintly orange for a short time. Shining UV at it seems to recharge the ability to glow from IR.
Summary of luminescence responses:
Sphalerite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Orange
- Fluorescence under Longwave (365nm LED) UV light: Blue
- Fluorescence under Longwave (365nm LED) UV light: Green
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Orange
- Afterglow after exposure to Longwave (365nm LED) UV light: Green
- Afterglow after exposure to Longwave (365nm LED) UV light: Orange
- Fluorescence under Midwave (305nm LED) UV light: Orange