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Formula: Ca2Mn3+3(PO4)3O2.3H2O
Hydrated phosphate, manganese-bearing mineral,
paramorph of robertsite
Crystal System: Monoclinic
Specific gravity: 3.22 measured, 3.21 calculated
Hardness: 2
Streak: Brown-red
Colour: Bronze, cinnamon-brown, yellow, dark red
Luminescence: Not fluorescent under UV
Environments
Pararobertsite occurs as fracture fillings in late-stage mineralisation in a phosphate-rich
granite
pegmatite
(Mindat).
Localities
At the type locality, the Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA,
pararobertsite occurs in secondary seams, as single
platy crystals 0.02 mm thick and up to 0.2 mm long and in clusters. These crystals occur on
whitlockite that encrustas several generations of
carbonate-apatite, which itself encrusts
quartz
(CM 27.3.451-455).
Pararobertsite from the Tip Top Mine -
Image
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