Formula: Mn7(PO4)2(OH)8
Anhydrous phosphate with hydroxyl, manganese-bearing mineral
Specific gravity: 3.55
Hardness: 4
Streak: Yellowish brown
Colour: Orange-brown to dark brown

Sedimentary environments
Metamorphic environments

Waterhouseite is a rare mineral that to date (September 2021) has been reported only from the type locality.


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 cummingtonitegrunerite. 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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