Beraunite

Beraunite is an iron phosphate mineral. It was first described by August Breithaupt for an occurrence in Beraun currently in the Czech Republic. Beraunite occurs as a secondary mineral in iron ore deposits, and as an alteration product of primary phosphate minerals in granite pegmatites.
Beraunite crystallizes in the monoclinic crystal system with point group 2/m. Beraunite’s formula is Fe2+ Fe3+5(OH)5(PO4)4·4H2O. Aluminium and zinc may substitute in the structure.