Allanpringite Locality: Mark Mine, Essershausen, Weilburg, Wetzlar, Hesse, Germany Field of view 6 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Allanpringite
Allanpringite is a phosphate mineral that was named after the Australian mineralogist, Allan Pring of the South Australian Museum. Allanpringite is a Fe3+ analogue of the 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.
Intro adapted from Wikipedia (CC BY-SA).
Allanpringite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Fe³⁺₃(PO₄)₂(OH)₃·5H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Wavellite structural group.
Key properties: Mohs hardness 3; specific gravity 2.562; refractive index 1.695; optically biaxial.
IMA symbol Apg, IMA status: approved, named in 2004.