Scientists from the Technical University of Munich (TUM) and the Ludwig-Maximilians-University Munich (LMU) report on the existence of pure Fluorine gas, inside a mineral called antozonite. Up until now Fluorine, the most reactive chemical known, was thought only to exist as part of chemical compounds such as fluorite. But a special type of fluorite rock known as antozonite or "fetid fluorite", because of the intensive odor it emits when crushed, has now been confirmed to contain Fluorine in its elemental form. The findings settle 200 years of debate on whether antozonite indeed contained this chemical element.