RICHELSDORFITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated arsenates
    Crystal system : Monoclinic
    Chemistry : Ca2Cu5Sb(AsO4)4(OH)6Cl 6H2O
    Rarity : Rare

Richelsdorfite is an arsenate from the oxidation zone of hydrothermal copper-arsenic deposits. Its name derives from its discovery locality : the Richelsdorf Mountains in Germany. Richelsdorfite is a blue to blue-green mineral that forms spherical aggregates and botryoidal incrustations, rarely small tabular crystals of 0.5 mm maximum. It usually accompanies other secondary copper minerals, notably arsenates (duftite, tyrolite) and forms preferentially at the contact of tetrahedrite and tennantite.

Main photo : Rhönite from Nickenicher Sattel, Germany © Edgar Müller

Richelsdorfite from Burrus Mine, Nevada, USA © Douglas Merson
Richelsdorfite from Clara mine, Germany © Michael Förch
Richelsdorfite from Triembach-au-Val, Bas-Rhin, France © Michael Förch
Richelsdorfite from Burrus Mine, Nevada, USA © Jason B. Smith

Richelsdorfite in the World

Richelsdorfite is known from quite a few deposits in Germany, particularly in the Harz (St-Andréasberg), in Hesse (Reichenbach, and in impregnations of Permian sandstones in the Richelsdorf mountains), and in Saxony (Ehrenfriedersdorf). It is also known at the Burrus mine (Nevada).

Richelsdorfite in France

In France, richelsdorfite is known in the Triembach-au-Val vein (Bas-Rhin) which has undoubtedly provided the best crystals in the world. It is also reported at Ste-Marie-aux-Mines (Haut-Rhin), at Salsigne (Aude), at Cap Garonne (Var) and at Laguépie (Tarn-et-Garonne).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 2
Density : 3
Fracture : Undetermined
Streak : Pale blue

TP : Translucent to transparent
RI : 1.640 to 1.694
Birefringence : 0.054
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : NoneRadioactivity : None