Fluorite, Marshall Co., AL, near Guntersville Dam
Contributed by: FMS Admin
Date: Mar 1st, 2026
Locality: Guntersville, Marshall County, Alabama, USA (See on Mindat)
Size: 7 x 5 x 10 cm
Weight: 334 g
Description:
This specimen was found in limestone riprap that was quarried nearby in now-closed quarries in Marshall County, AL. It consists mainly of gray limestone and nonfluorescent white or light-pink crystalline dolomite that surrounds a patch of amber fluorite. As shown here, the fluorite fluoresces in a strong yellow-white color under both LW and SW UV. But as the SW photo reveals, there is also some blue SW fluorescence around the periphery of the fluorite, possibly due to another activator in the fluorite or to the presence of a different mineral altogether (e.g., calcite).
Originally published by Bill Fowler on Nature’s Rainbows.
Summary of luminescence responses:
Fluorite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Yellow
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Yellow