Multi-Wavelength Calcite and Fluorite from the Denton Mine, Cave-In-Rock, Illinois
Contributed by: Chris Clemens
minID: 3Q9-8DL
Date: Apr 20th, 2026
Locality: Denton Mine, Harris Creek Mining Sub-District, Hardin County, Illinois, USA (See on Mindat)
Size: 7.3 x 4.7 x 12.6 cm
Weight: 352 g
Description:
This spectacular fluorescent specimen features multiple golden, twinned, calcite crystals on a matrix of dark purple, hydrocarbon-included fluorite, from the Denton Mine, Cave-In-Rock, Hardin County, Illinois.
This specimen shows a striking multi-wavelength fluorescent response under UV. The calcite fluoresces bright orange and the fluorite shows a blue/purple response under longwave UV (365nm). Note the bright white wisps, streaks and dots of fluorescent hydrocarbons in the fluorite. Under midwave UV (305nm), the calcite fluoresces a striking pink/magenta color, while the fluorite shows a subdued blue response. The calcite fluoresces orange/yellow and the fluorite shows a pale blue response under shortwave UV (254nm).
Located approximately 6.5 miles north of the town of Cave-In-Rock, the Denton Mine was operated by the Ozark-Mahoning Company from 1979 to 1993 and was one of the most productive fluorspar mines during the final years of mining in the Cave-In-Rock district.
Originally posted by Chris Clemens on Nature's Rainbows in 2019.
Summary of luminescence responses:
Calcite (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Orange
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: Pink
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Orange
- Fluorescence under Longwave (365nm LED) UV light: Blue
- Fluorescence under Midwave (305nm Lamp/Mercury) UV light: Blue
- Fluorescence under Shortwave (254nm Lamp/Mercury) UV light: Blue