Sellaite is a magnesium fluoride mineral with the formula MgF2. It crystallizes in the tetragonal crystal system, typically as clear to white vitrification prisms. It may be fibrous and occur as radiating aggregates. It has a Mohs hardness of 5 to 6 and a specific gravity of 2.97 to 3.15. Refractive index values are nω = 1.378 and nε = 1.390.
Discovery and occurrence
Sellaite was first described in 1868 and named for Italian mining engineer and mineralogist
Quintino Sella (1827–1884). Its type locality is the in France, where it occurred inside
bitumen-bearing dolomite-
anhydrite within a
moraine deposit. It has been reported in an
evaporite deposit at
Bleicherode; within
volcanic ejecta and
at
Vesuvius; in a
metamorphism magnesite deposit at ; and in
alkali soil granite near .
[
]
-
Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy, (7th edition), v. II, pp. 37–39
