Fontarnauite

Fontarnauite is a relatively recently described, rare sulfate, borate mineral with the chemical formula (Na,K)2(Sr,Ca)(SO4)[B5O8(OH)]*2H2O. It is found in an evaporite boron deposit. It coexists with other evaporite boron minerals, especially probertite. It is monoclinic, crystallizing in the space group P21/c.

It was named for Ramon Fontarnau i Griera, a materials scientist of the University of Barcelona.