Multi-Wavelength Calcite and Fluorite from the Denton Mine, Cave-In-Rock, Illinois

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. As seen in the composite photograph below, this specimen shows a striking multi-wavelength fluorescent response under UV.


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.

As seen in the photograph above, the calcite and fluorite show a differential fluorescent response dependent on the UV wavelength of excitation.

Under visible light (above), this specimen makes a lovely display piece. Well-formed, twinned, calcite scalenohedrons sit on a matrix of purple fluorite.

When viewed under long wave UV (365nm), as seen in the photograph above, the calcite fluoresces bright orange and the fluorite shows a blue/purple response. Note the bright white wisps, streaks and dots of fluorescent hydrocarbons in the fluorite.

Under mid wave UV (302nm), the calcite fluoresces a striking pink/magenta color, while the fluorite shows a subdued blue response.

When viewed under short wave UV (254nm), the calcite fluoresces orange/yellow and the fluorite shows a pale blue response.

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