Villiaumite

Villiaumite a rare halide mineral composed of sodium fluoride, NaF. It is very soluble in water and some specimens fluoresce under long and short wave ultraviolet light. It has a Mohs hardness of 2.5 and is usually red, pink, or orange in color.

The red color is due to a broad absorption peaking at 512 nm. It is a result of radiation damage to the crystal.

It was first described in 1908 for an occurrence in Los Islands, Guinea and named after the French explorer, Maxime Villiaume.