SCORODITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated arsenates
    Crystal system : Orthorhombic
    Chemistry : FeAsO4 2H2O
    Rarity : Uncommon


Scorodite is the most common alteration product of arsenopyrite and löllingite. The replacement of iron by aluminum is very low (less than 6% Al2O3), the solid solution to mansfieldite is therefore very limited. It is found in the oxidation zone of arsenic deposits in cryptocrystalline crusts of earthy or banded appearance, light green in color. Its name comes from the Greek skorodion (garlic) because this mineral gives off a garlic odor when heated. Scorodite crystals are rare, bipyramidal, elongated along [010] or flattened on {001}, most often millimetric, they can exceptionally exceed the centimeter. Bluish green to bottle green or greenish brown in natural light, some crystals can become blue to purple in artificial light (color change). It is an occasional ore of arsenic

Main photo : Scorodite from Cabrestante Mine, Zacatecas, Mexico © Jeffrey A. Scovil

Scorodite from Tsumeb, Namibia © Kyle Kevorkian
Scorodite from Baishiding Mine, Hezhou, China © Eugene & Sharon Cisneros
Banded scorodite from Djebel Debar, Algeria © Rock Currier
Scorodite from Franciman, Tarn, France © François Garric

Scorodite in the World

Among the very many scorodite localities, the El Cobre mine (Zacatecas, Mexico) has yielded extraordinary crystals blue-green of 15 mm scattered on quartz plates, that of Ojuela (Durango, Mexico) crystals of 3 cm, and that of Tsumeb (Namibia) large crystals measuring up to 4 cm. More recently crystals of 2 cm have been discovered at the Baishiding mine near Hezhou (Guangxi, China). Centimetric crystals are also known at Antonio Pereira, near Ouro Preto (Minas Gerais, Brazil), and beautiful blue-green specimens come from Dernbach (Hesse, Germany). At Gold Hill and Tintic (Utah), scorodite was sufficiently abundant to be used as an ore of arsenic. Djebel Debar (Algeria) has for its part provided large masses of banded concretions, of stalactiform appearance, of an original greenish, capable of taking a beautiful polish.

Scorodite in France

In France, scorodite is reported in very many occurrences, notably at Kaymar (Aveyron), Franciman (Tarn), Echassières (Allier), Rompas (Nièvre), La Verrière (Rhône), Vaulry (Haute-Vienne), Plessis (Finistère) and Ste-Marie-aux-Mines (Haut-Rhin).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.



Hardness : 3.5 to 4
Density : 3.27
Fracture : Sub-conchoidal
Streak : White-green


TP : Translucent
RI : 1.741 to 1.820
Birefringence : 0.027 to 0.036
Optical character : Biaxial +
Pleochroism : Low
Fluorescence : None


Solubility : Acids

Magnetism : NoneRadioactivity : None