Images
Formula: NaFe2+Fe3+2(PO4)3
Anhydrous phosphate, alluaudite group and forms a series
with
alluaudite
Crystal System: Monoclinic
Specific gravity: 3.4 to 3.5 measured, 3.67 calculated
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).
Back to Minerals