HETEROSITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal system : Orthorhombic
    Chemistry : FePO4
    Rarity : Quite common

Heterosite is a phosphate of iron and manganese which forms a continuous series with purpurite. It is a secondary phosphate coming from the alteration of primary phosphates (notably triphylite and lithiophilite) which is found in granitic pegmatites. Its name is taken from the Greek heteros (other), because it is the second manganese mineral discovered in the type locality : La Vilate near Chanteloube (Haute-Vienne). Heterosite does not form crystals but cleavable masses, sometimes triphylite pseudomorphs, or thin encrustations of dark pink, carmine red to purple, or purplish, turning brown-black then black by surface oxidation.


Main photo : Heterosite from Helen Beryl Mine, South Dakota, USA © Harold Moritz

Heterosite in the World

Heterosite is a relatively common phosphate. It is found in large masses in numerous American pegmatites in South Dakota (Tip-Top, Keystone, Bull Moose), Maine (Newry) and New Hampshire (Fletscher, Palermo). Among its many other deposits are the lepidolite pegmatites of the Karibib region (Namibia) and those of Sapucaia (Minas Gerais, Brazil).

Heterosite in France

In France, heterosite is reported in notable cleavable masses in the lepidolite pegmatites of St-Sylvestre and Chanteloube, in the Ambazac mountains (Haute-Vienne). It is also known in the pegmatites of Collioure (Pyrénées-Orientales).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 4 to 4.5
Density : 3.40
Fracture : Irregular
Streak : Light purple

TP : Opaque
RI : 1.861 to 1.911
Birefringence : 0.050
Optical character : Biaxial -
Pleochroism : Strong
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : NoneRadioactivity : None