PHOSPHOPHYLLITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Monoclinic
    Chemistry : Zn2(Fe,Mn)3(PO4)2 4H2O
    Rarity : Rare to very rare

Phosphophyllite, like azurite, crocoite or dioptase, is one of these very attractive minerals because of their magnificent colors. It is a rare phosphate of secondary origin present in pegmatites and in the oxidation zone of metal deposits. Its name comes from its chemical composition (phosphate) and the Greek phullon (leaf) in reference to its perfect cleavage. Phosphophyllite occurs in short prismatic or thick tabular crystals, commonly twinned with a superb blue-green to green color for the most sought after; however, they can also be colorless. This mineral fluoresces strongly in violet under short-wave UV. It can be exceptionally cut into gemstones.

Main photo : Twinned phosphophyllite from Unificada Mine, Cerro de Potosí, Bolivia © Brighton Rocks

Phosphophyllite from Cerro de Potosí, Bolivia © Rob Lavinsky
Phosphophyllite from Huayllani mine, Potosí, Bolivia © Alfredo Petrov
Twinned phosphophyllite from Rebentão Mine, Viseu, Portugal © Pedro Alves
Phosphophyllite from Hagendorf, Bavaria, Germany © Stephan Wolfsried

Phosphophyllite in the World

Phosphophyllite is a Bolivian mineral, with all the best crystals coming from this country. Two mines yielded extraordinary specimens : Unificada (Potosi) with its superb blue-green to green twinned crystals up to 15 cm (the best in the world), occupying cracks in the sulfide ore, and Siglo XX (Llallagua, Potosi ) with its 10 cm blue-green crystals. In the discovery deposit (the pegmatites of Hagendorf in Bavaria), the phosphophyllite appeared in small crystals, generally millimetric, but up to 3 cm. Excellent crystals are reported from the Red Hill pegmatite and other pegmatites of the same district of Rumford, Maine. It is also known in small crystals in the pegmatite of Palermo (New Hampshire) and in the oxidation zone of the Reaphook Hill zinc deposit (Australia).

Phosphophyllite in France

Twins are known on {100} forming fishtails (they can be polysynthetic) and more rarely on {102}.

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3 to 3.5
Density : 3.08 to 3.13
Fracture : Irregular
Streak : White

TP : Translucent to transparent
RI : 1.595 to 1.620
Birefringence : 0.021
Optical character : Biaxial -
Pleochroism : None
Fluorescence : Purple

Solubility : Acids

Magnetism : NoneRadioactivity : None