| Greifensteinite | |
|---|---|
 Greifensteinite (picture size: 3 mm) | |
| General | |
| Category | Phosphate mineral Roscherite group |
| Formula (repeating unit) | Ca2Fe5Be4(PO4)6(OH)4·6H2O |
| IMA symbol | Gfs |
| Strunz classification | 8.DA.10 |
| Dana classification | 42.7.7.4 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/c |
| Unit cell | a = 15.903, b = 11.885 c = 6.677 ; β = 94.68°; Z = 2 |
| Identification | |
| Color | Yellow green, olive green, light brown |
| Crystal habit | Prismatic |
| Cleavage | Good on {100} (or parting on {100}) |
| Fracture | Uneven |
| Tenacity | brittle |
| Mohs scale hardness | 4.5 |
| Luster | Vitreous |
| Streak | White, greenish |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.93 |
| Optical properties | Biaxial (-) |
| Refractive index | nα: 1.624 nβ: 1.634 nγ: 1.638 |
| Birefringence | 0.014 |
| 2V angle | 80° |
| References | |
Greifensteinite is beryllium phosphate mineral with formula: Ca2Fe5Be4(PO4)6(OH)4·6H2O. 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.
References
- Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Greifensteinite data on Webmineral
- Mindat.org
- Mineralienatlas
- Roscherite group on Mindat.org
- Rastsvetaeva R K, Gurbanova O A, Chukanov N V (2006) Crystal structure of greifensteinite Ca2Fe☐Mg2Fe2Be4(PO4)6(OH)4·6H2O. Doklady Chemistry 41, 18-25