LÖLLINGITE

    Class : Sulfides and sulfosalts
    Subclass : Arsenides
    Crystal system : Orthorhombic
    Chemistry : FeAs2
    Rarity : Uncommon

Löllingite (or loellingite) is an uncommon iron arsenide. It is mainly found in high temperature hydrothermal deposits, often in conjunction with granitic intrusions : gold, stanno-wolframiferous or polymetallic veins and sometimes in pegmatites and skarns. It owes its name to its locality of discovery : Lölling (Austria). Löllingite can form elongated, striated, bipyramid prismatic crystals, but usually occurs in flabelliform break masses, bacillary aggregates, or fibroradiated nodules. Its luster is metallic, its silver-white color tarnishing quite quickly to a light steel gray. Like arsenopyrite, it easily alters to scorodite in outcrops. It is sometimes an arsenic ore.

Main photo : 7 cm löllingite from Huanggang, Inner Mongolia, China © Rob Lavinsky

Löllingite from Oumlil Mine, Morocco © Jean-Vincent Coureau
Löllingite from Gabe Gottes, Ste-Marie-aux-Mines, Haut-Rhin, France © Michel Bretheau
Löllingite from Huanggang, Inner Mongolia, China © Jean-François Carpentier
Löllingite from Carlés Mine, Asturias, Spain © José Rafael Gonzalez Lopez

Löllingite in the World

The most beautiful known crystals were discovered in 2012 in Huanggang (Inner Mongolia, China) where they measure up to 7 cm, the tin-bearing veins of Tazna (Bolivia) produced crystals measuring 4 cm. Superb crystals and masses weighing up to 300 kg have been extracted from the Bob Ingersoll pegmatite near Keystone (South Dakota). Finally, beautiful crystals forming fibroradiated aggregates were discovered in the cobalt and nickel mine of Bou-Azzer (Morocco).

Löllingite in France

In France, löllingite is said to have provided 4 cm crystals at Vaulry (Haute-Vienne) and it is also known in beautiful specimens at the Chalanches mine (Isère). It is also found in microcrystals in the polymetallic veins of Ste-Marie-aux-Mines (Haut-Rhin).

Twinning

Twins are known on {001} and polysynthetics on {101}.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 5 to 5.5
Density : 7.43
Fracture : Sub-conchoidal
Streak : Gray-black

TP : Opaque
RI : -
Birefringence : -
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None