The Illinois fluorite deposit has some regions where hydrocarbons have seeped up from the depths and interacted with the fluorite. Every now and then, such a combination becomes stable and is preserved. Here we have a nice, gemmy Fluorite with classic Minerva phantoms: yellow core with purple and blue outer zones. The crystal faces have a finely stepped growth, causing the luster to be more silky than normal. What is exceptional about this miniature, however, is the unusually heavy coating of hydrocarbons, which adds visual and mineralogical interest. Mined in 1991, this is a good representative piece of a unique association. RCL 1580