Wiktionary
greifensteinite
n. (context mineral English) A monoclinic-prismatic dark olive green mineral containing aluminum, beryllium, calcium, hydrogen, iron, magnesium, manganese, oxygen, and phosphorus.
Wikipedia
Greifensteinite
Greifensteinite is beryllium phosphate mineral with formula: CaFeBe(PO)(OH)ยท6HO. It is the Fe dominant member of the roscherite group. 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-rich pegmatite in miarolitic cavities. It was approved by the International Mineralogical Association in 2002.