Natural Fluorine Does Exist ... In Smelly Rocks

scibri writes "Chemists have proved that a smelly rock is the only known place on Earth where fluorine exists in its elemental form, F2 (Abstract). The rock is antozonite, a calcium fluoride (fluorite) mineral that is dark violet or even black in colour, also known as fetid fluorite or stinkspar. Needless to say, this rock stinks. The pungent smell is given off when antozonite is crushed, and chemists and mineralogists have argued over the origin of the stench since the early nineteenth century. It turns out French chemist Henri Moissan, who first isolated fluorine in 1886, was right. The rock contains pockets of fluorine that are released on crushing."

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Radiation produced fluorine

[AlienIntelligence]

Clues from previous experiments suggested how fluorine might be formed in the rocks. The experiments exposed artificial calcium fluoride to - and -radiation, and high-energy electron beams. The samples often turned violet, because the radiation was splitting calcium fluoride apart to form clusters of calcium ions. Subsequent tests showed that bubbles of fluorine gas were also forming in the lenses.

The same process could explain the stench of antozonite, says Kraus. The mineral contains tiny amounts of radioactive uranium-238, which decays into -emitting daughter nuclides. The rocks have been lying around for 100 million years, says Kraus, which is enough time for the radioactive decay to produce the same effect as seen in the artificial fluorite experiments.

Interesting stuff to a rock nerd.

-AI