Republic of the Congo

It was picked out of the crushed residue of a drill core through buried salt beds.

Wendling, von Hodenberg and Kuhn described congolite in 1972 in the German journal Kali und Steinsalz, from sedimentary evaporites near Brazzaville. It is the trigonal iron analog of boracite and sits in a phase series with trembathite. Its only other well-documented occurrence is the Penobsquis potash mine in New Brunswick, Canada.