Fluorite, Sturgeon Bay, Wisconsin

Contributed by: Chris Clemens
minID: WCM-00R
Date: Apr 19th, 2026
Locality: Sturgeon Bay, Door County, Wisconsin, USA (See on Mindat)
Size: 18 x 13 x 22 mm
Weight: 7 g

Description:
Fluorite is not a commonly occurring mineral species in the state of Wisconsin, but here\'s a rare example of the elusive Wisconsin fluorite. This specimen has an interesting story- it was found in the Sturgeon Bay area (Door County) during the excavation of a new parking lot. This example shows amber colored fluorite cubes on a minor matrix of calcite and dolomite. The fluorite is brightly fluorescent and phosphorescent under all UV wavelengths.

The bright, multi-wavelength fluorescence and phosphorescence/afterglow of this Sturgeon Bay fluorite specimen is activated by organic inclusions within the fluorite. Note the zoning of the response.

Originally posted by Chris Clemens on Nature's Rainbows in 2020.

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:

Fluorite (Mindat) (RRUFF)

• Fluorescence under Longwave (365nm LED) UV light: Yellow
• Afterglow after exposure to Longwave (365nm LED) UV light: Green
• Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: White
• Afterglow after exposure to Shortwave (254nm Lamp/Mercury) UV light: Blue