Greifensteinite is beryllium phosphate mineral with formula: Ca2Fe2+5Be4(PO4)6(OH)4·6H2O. It is the Fe2+ dominant member of the roscherite It crystallizes in the monoclinic crystal system and typically forms prismatic dark olive green crystals.
It was first described in Germany at Greifenstein Rocks, Ehrenfriedersdorf , and was named for the location. At the type locality , it occurs within a lithium cavities. It was approved by the International Mineralogical Association