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Formula: Mn7(PO4)2(OH)8
Anhydrous phosphate with hydroxyl, manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.55 measured, 3.591 calculated
Hardness: 4
Streak: Yellowish brown
Colour: Orange-brown to dark brown
Environments
Sedimentary environments
Metamorphic environments
Waterhouseite is a rare mineral that to date (September 2021) has been reported only from the type
locality.
Localities
The type Llocality, the Iron Monarch open cut, Iron Knob, Middleback Range, Eyre Peninsula, South Australia, is the
largest of a number of sedimentary iron ore deposits in the Middleback Ranges of
South Australia. The orebody lies within a carbonate-facies iron formation,
composed primarily of iron carbonate, silica and
iron oxide, with primary
iron silicates such as iron-rich
talc and
cummingtonite–grunerite.
Hematite and quartz become predominant
at the top of the sequence and constitute the orebody.
Waterhouseite occurs as divergent sprays of bladed
crystals up to 1 mm in length and up to 20 µm in thickness in cavities in a matrix consisting of
hematite, hausmannite,
baryte, manganese-bearing
calcite and rhodochrosite.
Shigaite, gatehouseite,
seamanite, rhodochrosite,
baryte, hausmannite and
hematite are found in close association with waterhouseite.
Metaswitzerite, sussexite,
arsenoclasite, collinsite,
pyrobelonite and triploidite
have also been noted on specimens from the same immediate area of the open cut, but not in direct association with
waterhouseite
(CM 43.1401-1410).
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