Calcium Fluoride - Source of Fluorine Gas

Source of Fluorine Gas

In 2012, the first source of naturally occurring fluorine gas was found in fluorite mines in Bavaria, Germany. It was previously thought that fluorine gas did not occur naturally because it is so reactive and would rapidly react with other chemicals. Fluorite is normally colourless but some varied forms found nearby look black and are known as 'fetid fluorite' or antozonite. The minerals, containing small amounts of uranium and its daughter products, release radiation sufficient enough to cause the fluoride anions within the structure to group together, forming fluorine gas; this gas then becomes trapped inside the mineral until it can diffuse out. The colour of fetid fluorite is predominantly due to the calcium atoms remaining. Solid state fluorine-19 NMR was carried out on the gas escaping the antozonite, and a peak was found at 425 ppm which is consistent with the difluoride structure of F₂.