PHOSPHOFERRITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Orthorhombic
    Chemistry : Fe3(PO4)2 3H2O
    Rarity : Rare to uncommon

Phosphoferrite is an iron and manganese phosphate which forms a series with reddingite, the purely manganiferous pole. It is a secondary phosphate of granitic pegmatites, in which it often constitutes an alteration product of triphylite. Its name is derived from its chemical composition : phosphorus and iron. Phosphoferrite is colorless to pale green and olive green, but changes to reddish-brown through alteration. Its crystals are tabular with a frequent appearance of pseudo-octahedra ; it is also found massive or coarsely fibrous.

Main photo : Phosphoferrite from Palermo, New Hampshire, USA © Scott M. Whittemore

Phosphoferrite in the World

The largest phosphoferrite crystals come from the Hagendorf pegmatite (Bavaria, Germany) where tabular to pseudo-octahedral individuals reach one centimeter. Phosphoferrite is also present in American pegmatites from South Dakota, in the Custer and Keystone districts (Tip Top, Bull Moose, etc...), and from New Hampshire to Palermo. Finally, it exists in the Brazilian pegmatite of Lavra do Enio (Minas Gerais) and in that of Mangualde (Portugal).

Right photo : Phosphoferrite from Hagendorf, Bavaria, Germany © Uwe Haubenreisser


Phosphoferrite in France

In France, phosphoferrite is reported in Crozant (Creuse) and Pla Soulcem (Ariège).

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3 to 3.5
Density : 3 to 3.2
Fracture : Irregular
Streak : White

TP : Translucent to transparent
RI : 1,663 to 1,700
Birefringence : 0.036
Optical character : Biaxial +
Pleochroism : None
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None