Scheele and many later investigators, including Davy, Gay-Lussac, Lavoisier, and Thenard, experimented with hydrofluoric acid some experiments ended in tragedy. It occurs chiefly in the minerals fluorspar , CaF2, and cryolite , Na3AlF6. Because of its very great chemical activity, fluorine is very hard to prepare and very hard to store. Modern commercial production methods are essentially variations on the procedures first used by Moisson. Fluorine is about one and one-third times, as heavy as air.
Fluorine is the most electronegative and reactive of all elements.
With the exception of some of the inert gases, fluorine reacts violently with metals and forms compounds with all elements including organic and inorganic substances. A stream of hydrogen ignites instantly when in contact with fluorine forming hydrogen fluoride. Fluorine reacts vigorously with water liberating oxygen as ozone and forming hydrogen fluoride. Finely divided metals, glass, ceramics, carbon, and water burn in fluorine with a bright flame. In much of this century it was also used in aerosol propellants.