Ludlamite - Encyclopedia

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Monoclinic
    Chemistry : Fe3(PO4)2 4H2O
    Rarity : Quite common

Ludlamite is a secondary mineral of iron and manganese deposits, also present in phosphate alteration in certain pegmatites. Its name was given to it in honor of the English mineral collector Henry Ludlam. Ludlamite is composed of flattened or elongated tabular crystals, sometimes ending in a roof, frequently assembled in centimetric tufts and tufts, in parallel groups, and in compact grained masses. Its apple green to olive green color is quite characteristic.

Main photo : Ludlamite from Huanuni mine, Oruro, Bolivia © Gianfranco Ciccolini

Ludlamite from San Antonio Mine, Chihuahua, Mexico © Michael Roarke
Ludlamite from San Antonio Mine, Chihuahua, Mexico © Rob Lavinsky
Ludlamite from Wheal Jane, Cornwall, England © Eugene & Sharon Cisneros
Ludlamite and pyrite from Salsigne, Aude, France © Frédéric Bonnet

Ludlamite in the World

The beautiful crystals come from the pegmatites of Hagendorf (Germany) and especially from the deposits of Wheal Jane (Truro, English Cornwall) and Strari Trg (Trepca, Kosovo) in which the magnificent 3 cm crystals are considered the most beautiful in the world before the discovery of deposits in South America. Indeed, larger and also very aesthetic crystals come from San Antonio (Chihuahua, Mexico) and the Bolivian deposits of Huanuni and Morococata. The pegmatites of the Black Hills in South Dakota (Keystone and Custer districts) provided some good crystals but especially masses of ludlamite exceeding 30 cm.

Ludlamite in France

In France, quality ludlamite crystals measuring 3 cm, implanted on pyrite, are known at the Salsigne gold mine (Aude). The Crozant deposit (Creuse) also provided some specimens of this mineral.

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 3.5
Density : 3.12 to 3.19
Fracture : Undeterminated
Streak : Green white

TP : Translucent to transparent
RI : 1.650 to 1.697
Birefringence : 0.038 to 0.044
Optical character : Biaxial +
Pleochroism : None
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None

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