Mitridatite

phosphate

pegmatite

Formula: Ca2Fe3+3O2(PO4)3.3H2O
Hydrated phosphate, forms a series with arseniosiderite
Specific gravity: 3.25
Hardness: 2½
Streak: Pale green
Colour: Greenish-yellow, olive green, brownish-green, etc.
Solubility: Soluble in hot acids.
Environments:

Pegmatites
Sedimentary environments

Mitridatite is a common stain or crust on minerals near oxidising ferrous phosphate minerals, typically triphylite or vivianite in granite pegmatites; it is a component of cement or fossil replacements in some ferruginous oolitic sediments, and it occurs in phosphatic soils. Associated minerals include diadochite, triphylite, vivianite, rockbridgeite, heterosite, hureaulite, fairfieldite, cyrilovite, jahnsite, laueite, collinsite, apatite, strunzite and iron hydroxides (HOM, Mindat)

At the Moculta quarry, Angaston, Barossa Valley, Mount Lofty Ranges, South Australia, mitridatite is associated with fluorapatite and leucophosphite (AJM 17.1.22).

At Tom's quarry, Kapunda, Mount Lofty Ranges, South Australia, mitridatite is found within the natrodufrénite - leucophosphite - kapundaite assemblage associated with fluorapatite and leucophosphite, and rarely with ushkovite and xanthoxenite (AJM 17.1.22).

At the co-type localities, Mount Mithridat and the Kerchenskoe deposit, both on the Kerch Peninsula, Crimea, Russia, mitridatite occurs in oolitic sedimentary iron ores associated with vivianite and anapaite (Mindat).

Paragenesis

The sequence triphylite - ferrisicklerite - rockbridgeite - leucophosphite - hureaulite + laueite - mitridatite - bermanite - todorokite appears repeatedly at the Tip Top, White Elephant and Linwood pegmatites in the Black Hills, Custer county, South Dakota, USA, at Hagendorf, Bavaria, Germany, at Palermo Number 1, New Hampshire, USA and at the Sapucaia pegmatite, Brazil. At the White Elephant pegmatite, Mitridatite is a particularly persistent phase at all stages of late crystallisation and occurs widely as stains coating the silicates surrounding triphylite crystals at practically every pegmatite where triphylite occurs, suggesting that mitridatite is an important low temperature phase. (AM 59.48-59).

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