Allanpringite

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Allanpringite
Allanpringite-122708.jpg
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]

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]

References[edit]

  1. ^ a b Allanpringite. Mindat
  2. ^ Allanpringite. Webmineral
  3. ^ 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