Arrojadite

arrojadite

graftonite

cassiterite

spodumene

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Formulae:
arrojadite-(BaFe): BaFe²⁺(CaNa₂)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂
arrojadite-(BaNa): BaNa₃(NaCa)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂
arrojadite-(KFe): (KNa)Fe²⁺(CaNa₂)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂
arrojadite-(KNa): KNa₃(CaNa₂)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂
arrojadite-(PbFe): PbFe²⁺(CaNa₂)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂
arrojadite-(SrFe): SrFe²⁺(CaNa₂)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂

Data for arrojadite-(KFe):
Originally named arrojadite and redefined after the new arrojadite nomenclature in October 2005.
Anhydrous phosphate containing hydroxyl, arrojadite group, forms a series with dickinsonite
Crystal System: Monoclinic
Specific gravity: 3.5 to 3.6
Hardness: 5
Colour: Olive-green
Environments

Pegmatites

There are two co-type localities, the Serra Branca pegmatite, Pedra Lavrada, Paraíba, Brazil, and the Nickel Plate mine, Keystone, Keystone Mining District, Pennington county, South Dakota, USA. At the Nickel Plate mine arrojadite occurs in large masses in the granite pegmatites associated with graftonite, cassiterite, spodumene, beryl, quartz and muscovite. Arrojadite and cassiterite are intimately intergrown. Arrojadite is possibly replaced by quartz and by graftonite (AM 35.59-76, HOM, Dana).

At the Palermo No. 1 and No. 2 mines, Groton, Grafton county, New Hampshire, USA, arrojadite is a high-temperature (~800^oC) primary mineral in granite pegmatites (HOM).

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