Allanpringite
| Allanpringite | |
|---|---|
|
Picture width 4 mm | |
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | Fe3+3(PO4)2(OH)3·5H2O |
| Strunz classification | 08.DC.50 |
| Dana classification | 42.10.02.02 |
| Crystal symmetry | Monoclinic – prismatic, H-M symbol (2/m), space group P21/n |
| Unit cell | a = 9.777 Å, b = 7.358 Å, c = 17.83 Å, Z = 4; β = 92.19° |
| Identification | |
| Formula mass | 498.07 g |
| Color | Pale brownish yellow |
| Crystal habit | Acicular |
| Cleavage | {hk0} perfect, {010} good |
| Fracture | Irregular/uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 3 |
| Luster | Vitreous |
| Streak | Pale yellowish white |
| Diaphaneity | Translucent to transparent |
| Specific gravity | 2.54 (meas.), 2.583 (calc.) |
| Optical properties | Biaxial (+) |
| Refractive index |
nα = 1.662 nβ = 1.675 nγ = 1.747 |
| Birefringence | 0.085 |
| 2V angle | 48° (calc.) |
| References | [1][2] |
Allanpringite is a phosphate mineral named after Australian mineralogist Allan Pring, South Australian Museum. Allanpringite is a Fe3+ analogue Al-phosphate mineral wavellite, but it has a different crystal symmetry – monoclinic instead of orthorhombic in wavellite. It forms needle-like crystals, which are always twinned and form parallel bundles up to about 2 mm long. They are often found in association with other iron phosphates in abandoned iron mines.[1]
References
- 1 2 Allanpringite. Mindat
- ↑ Allanpringite. Webmineral
This article is issued from Wikipedia - version of the Friday, March 01, 2013. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.