| Greifensteinite | |
| Category: | Phosphate mineral Roscherite group |
| Formula: | Ca2Fe2+5Be4(PO4)6(OH)4·6H2O |
| Imasymbol: | Gfs[1] |
| Strunz: | 8.DA.10 |
| Dana: | 42.7.7.4 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | C2/c |
| Unit Cell: | a = 15.903, b = 11.885 c = 6.677 [Å]; β = 94.68°; Z = 2 |
| Color: | Yellow green, olive green, light brown |
| Habit: | Prismatic |
| Cleavage: | Good on (or parting on) |
| Fracture: | Uneven |
| Tenacity: | brittle |
| Mohs: | 4.5 |
| Luster: | Vitreous |
| Streak: | White, greenish |
| Diaphaneity: | Transparent to translucent |
| Gravity: | 2.93 |
| Opticalprop: | Biaxial (-) |
| Refractive: | nα: 1.624 nβ: 1.634 nγ: 1.638 |
| Birefringence: | 0.014 |
| 2V: | 80° |
| References: | [2] [3] [4] |
Greifensteinite is beryllium phosphate mineral with formula: Ca2Fe2+5Be4(PO4)6(OH)4·6H2O. It is the Fe2+ dominant member of the roscherite group.[5] It crystallizes in the monoclinic crystal system and typically forms prismatic dark olive green crystals.[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.[2]