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Barite and Calcite from the Minerva No. 1 Mine, Cave-In-Rock, Illinois

This very delicate and aesthetic specimen is from the historic Minerva No. 1 Mine in the Illinois-Kentucky Fluorspar District of Southern Illinois, located in Cave-In-Rock, Hardin County, Illinois. This piece features delicate bladed crystals of barite sitting on top of interspersed calcite crystals on a limestone matrix. Minor fluorite is also present. The size of this specimen is 15.6 x 11.8 x 4.6 cm and it weighs 490 grams. As shown in the photographs below, the best fluorescent response is seen under mid wave UV.

When viewed under mid wave UV (302 nm), the barite shows a bright white response and the calcite fluoresces a beautiful pastel pink. The limestone matrix is not fluorescent. This specimen is at its best when viewed under mid wave UV.

Under short wave UV (254 nm) the barite shows pale blue-white fluorescence while the calcite shows a moderate orange response.

As shown in the photograph above, an underlying layer of purple fluorescent fluorite becomes visible under long wave UV (365 nm), while the barite shows a white response and the calcite fluoresces a moderate to dim peach/orange.

Same specimen shown under visible light. Delicate bladed crystals of colorless barite sit on top of interspersed pale yellow/amber calcite crystals on a limestone matrix. An underlying layer of purple fluorite is also present.

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