Hureaulite

phosphate

triphylite

Formula:Mn2+5(PO3OH)2(PO4)2.4H2O
Hydrated acid phosphate
Specific gravity: 3.15 to 3.20
Hardness: 5
Streak: Nearly white
Colour: Commonly pink to colourless, also red, orange, orange-red, reddish brown, yellowish brown, violet-rose, amber, grey
Solubility: Readily soluble in acids
Environments

Pegmatites

Hureaulite is a late-stage secondary mineral formed by alteration of primary phosphates in complex granite pegmatites, associated with lithiophilite, triphylite, heterosite, rockbridgeite, cacoxenite, vivianite, fairfieldite, dickinsonite, eosphorite, stewartite, strengite, phosphosiderite, roscherite, hydroxylapatite, jahnsite, lithiophilite and triplite (HOM, Mindat).
Hureaulite is one of the more persistent low temperature transition metal phosphate hydrates derived from hydrothermal attack of triphylite-lithiophilite crystals in granite pegmatites. Hureaulite characteristically occurs very late in the secondary phosphate paragenetic sequence (AM 58.302-307).

At the type locality, Les Hureaux, Saint-Sylvestre, Haute-Vienne, Nouvelle-Aquitaine, France, hureaulite occurs in a zone of altered triphylite in a granite pegmatite, associated with rockbridgeite, cacoxenite, and vivianite in cavities in heterosite (Dana, Mindat).

At the Stewart pegmatite, Pala, San Diego county, California, USA, hureaulite occurs with sicklerite, phosphosiderite and stewartite in altered lithiophilite (Dana, AM 70.395-408).

At Branchville, Ridgefield, Fairfield county, and the Strickland Quarry, Portland, Middlesex county, Connecticut, USA, hureaulite is a secondary mineral found with fairfieldite, dickinsonite, reddingite, and eosphorite as hydrothermal alteration of lithiophilite (Dana).

At the Palermo number 1 and Fletcher mines, Groton, Grafton county, New Hampshire, USA, hureaulite occurs in weathered triphylite with phosphosiderite, strengite and heterosite (Dana).

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