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Formula: Fe3+Fe3+2(PO4)2(OH)3.5H2O
Hydrated phosphate containing hydroxyl, strunzite group,
paramorph of
laueite and stewartite
Crystal System: Triclinic
Specific gravity: 2.38 to 2.50 measured, 2.55 calculated
Hardness: 4
Streak: White
Colour: Pale yellow to creamy white, tan to very light brown
Environments
Pegmatites
Sedimentary environments
Hydrothermal environments
Ferristrunzite occurs in granite
pegmatites and in sedimentary phosphate nodules
(Mindat).
It is probably an oxidation product of strunzite
(HOM).
Localities
At the type locality, Mont-des-Groseillers, Blaton, Bernissart, Hainaut, Wallonia, Belgium, ferristrunzite occurs
as light brownish-yellow matted aggregates of acicular crystals, 2 to 30 microns long; composites are up to 0.5 mm
long and radiating sprays are up to 2.6 mm in diameter.
The ferristrunzite is associated with crandallite,
diadochite,
allophane-evansite,
minyulite, strengite,
phosphosiderite,
cacoxenite
and beraunite, as a
secondary mineral in argillaceous and clastic sediments
exposed in a canal
(AM 74.502).
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