Greifensteinite is beryllium phosphate mineral with formula: Ca2Fe2+5Be4(PO4)6(OH)4·6H2O.

It is the Fe2+ dominant member of the roscherite group.

[2] 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-rich pegmatite in miarolitic cavities.

It was approved by the International Mineralogical Association in 2002.