Ferroalluaudite

minerals

ludlamite

arrojadite

vivianite

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Formula: NaFe2+Fe3+2(PO4)3
Anhydrous normal phosphate, alluaudite group and forms a series with alluaudite
Specific gravity: 3.4 to 3.5
Hardness: 5 to 5½
Streak: Straw-yellow
Colour: Straw-yellow to brownish yellow, green, greenish black; yellow to yellow-green in transmitted light
Solubility: Soluble in acids
Environments

Pegmatites
Sedimentary environments

Ferroalluaudite occurs in zoned granite pegmatites and in phosphatic nodules. Associated minerals include triphylite, barbosalite, ferrisicklerite and apatite (HOM).

Localities

The type locality is Chanteloube, Razès, Bellac, Haute-Vienne, Nouvelle-Aquitaine, France.

At the Palermo No. 1 Mine, Groton, Grafton county, New Hampshire, USA, in a pegmatite, crystals of ferroalluauditemore or less replaced by ludlamite are found along one side of a pod, associated with arrojadite embedded in siderite, ludlamite and vivianite masses, which are within quartz-mica-perthite (a variety of feldspar) at the core of the pegmatite (Dana).

Alteration

Ferroalluaudite occurs as an alteration product of varulite and arrojadite-(KFe), and itself alters to heterosite and purpurite (Mindat).

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