Fluorite with Hydrocarbon Inclusions, Minerva No. 1 Mine, Cave-In-Rock, Illinois

It is not uncommon for fluorite specimens mined from the historic Illinois-Kentucky Fluorspar District to contain bitumen, oil or other hydrocarbon inclusions. Often, these hydrocarbon inclusions will show bright fluorescence under UV, sometimes producing a spectacular luminescent effect. This specimen, collected from the famous Minerva No. 1 Mine (Cave-In-Rock, Hardin Co., IL), provides a beautiful example of brightly fluorescent hydrocarbon inclusions.

Fluorescent hydrocarbon inclusions are seen as bright blue/white dots within the fluorite cubes. This photograph was taken under long wave UV (365 nm). The largest crystal measures 28 mm on the upper edge.



Same view as seen in the photograph above, showing fluorescence under short wave UV (254 nm).


Same view as seen in the two photograph above, taken under visible light.



The following series of photographs show the specimen, beginning as a full view, and then at increasingly higher levels of magnification

Full view of specimen, shown under visible light. This piece measures 10.4 x 6.2 x 5.0 cm, and weighs 417 grams.


Full view of specimen showing fluorescence under long wave UV (left) and short wave UV (right). Click on image for a larger view.



Close-up view of main fluorite cube (28 mm on upper edge) shown under visible light (left), long wave UV (middle) and short wave UV (right). Click on image for a larger view.



Macro view of main fluorite cube, FOV = 6.8 mm, shown under visible light (left), long wave UV (middle) and short wave UV (right). Click on image for a larger view.

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