LITHIOPHILITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal system : Orthorhombic
    Chemistry : LiMnPO4
    Rarity : Quite common


Lithiophilite (or lithiophyllite) is a primary manganese and lithium phosphate present exclusively in sodolithic granitic pegmatites. It forms a continuous series with triphylite, its iron-bearing counterpart. Its name comes from its chemistry (lithium) and the Greek philos (friend) which highlights the abundance of this element in its composition. Brown in color, generally translucent to opaque, lithiophilite most often forms cleavable to compact masses that can reach considerable dimensions (up to 5 m); well individualized, prismatic crystals with pseudohexagonal sections are very rare. The atmospheric and hydrothermal alteration of lithiphillite is responsible for the formation of numerous secondary phosphates (sicklerite, heterosite and purpurite when lithium is eliminated). This progressive transformation gives the mineral a black surface color which spreads along the cleavages, drawing a grid.

Main photo : 1.7 cm lithiophilite from Foote Lithium Co. Mine, North Carolina, USA © Rob Lavinsky

Lithiophilite from Foote Lithium Co. Mine, North Carolina, USA © Jason B. Smith
Lithiophilite from Foote Lithium Co. Mine, North Carolina, USA © Jason B. Smith
Lithiophilite from Foote Lithium Co. Mine, North Carolina, USA © Stephan Wolfsried
Lithiophilite from Foote Lithium Co. Mine, North Carolina, USA © Jason B. Smith

Lithiophilite in the World

Lithiophilite is common in most pegmatites of Maine and Connecticut, and especially of South Dakota (Custer), in metric masses and centimeter-sized crystals of good quality. The Portuguese pegmatite from Mangualde as well as the lepidolite pegmatite from Karibib (Namibia) also provided good centimeter-sized crystals.

Lithiophilite in France

In France, lithiophilite is present in the sodolithic pegmatites of the Ambazac mountains in Limousin (Saint-Sylvestre, Chanteloube) which gave strongly altered cleavable masses, sometimes decimetric in size.

Twinning

Contact twins on {130} are known but rare.

Fakes and treatments

No fakes recorded for this mineral species.



Hardness : 4
Density : 3.29 to 3.50
Fracture : Undetermined
Streak : White to pale yellow


TP : Translucent to transparent
RI : 1.663 to 1.691
Birefringence : 0.010
Optical character : Biaxial +
Pleochroism : Low
Fluorescence : None


Solubility : Acids

Magnetism : NoneRadioactivity : None