Allanpringite
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][3]
| Allanpringite | |
|---|---|
 Picture width 4 mm | |
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | Fe3+3(PO4)2(OH)3·5H2O |
| Strunz classification | 8.DC.50 |
| Dana classification | 42.10.02.02 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/n |
| Unit cell | a = 9.777, b = 7.358 c = 17.83 [Å]; β = 92.19°; Z = 4 |
| Identification | |
| Formula mass | 498.07 g/mol |
| 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] |
References
- Allanpringite. Mindat
- Allanpringite. Webmineral
- Kolitsch, U., Bernhardt, H.J., Lengauer, C.L., Blass, G., and Tillmanns, E., 2006. Allanpringite, Fe3(PO4)2(OH)3·5H2O, a new ferric iron phosphate from Germany, and its close relation to wavellite. European Journal of Mineralogy 18, 793-801
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