Formula: Mn2+Mn2+Mg2Al2(PO4)4(OH)2.8H2O
Hydrated phosphate containing hydroxyl, whiteite subgroup,
jahnsite group,
manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.61 measured
Hardness: 4
Streak: Pale orange
Colour: Reddish orange
Environments
Sedimentary environments
Hydrothermal environments
Localities
The type locality, the Iron Monarch open cut, Iron Knob, Middleback Range, Eyre Peninsula, South Australia,
lies within an iron formation composed primarily of iron carbonate, silica, and iron oxide, with
primary iron silicates such as iron-rich
talc and
cummingtonite–grunerite. The
orebody contains pods of high-grade manganese ore. Whiteite-(MnMnMg)
was collected from a manganese-rich, carbonate-rich zone, comprising hematite,
hausmannite, baryte,
manganese-rich calcite and
rhodochrosite. Carbonate-rich veins host a number of
secondary phosphate, arsenate, vanadate, and sulphate minerals
that formed as late-stage, low-temperature hydrothermal phases. An unusual feature of the
secondary minerals from this zone is that many of them contain
no Fe, even those that would readily accommodate it, such as collinsite,
fairfieldite, gatehouseite,
arsenoclasite, triploidite,
waterhouseite and whiteite-(MnMnMg). This suggests that the source
of the hydrothermal fluids from which these minerals crystallised was a region with a low concentration of Fe
(CM 57(2).215-223).
The whiteite-(MnMnMg) was found as a single unterminated prismatic crystal associated with
triploidite and rhodochrosite
(Mindat).
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