ROEDDERITE

    Class : Silicates
    Subclass : Cyclosilicates
    Crystal system : Hexagonal
    Chemistry : (Na,K)2(Mg,Fe)5Si12O30
    Rarity : Very rare

Roedderite is a very rare silicate that forms a series with eifelite. It is found in highly metamorphic xenoliths brought to the surface by leucite tephrites, and in meteorites (chondrites and octahedrites). It was named in honor of Edwin Woods Roedder, a geologist at the US Geological Survey. Roedderite crystals are lamellae and short hexagonal prisms that do not exceed 6 mm, they are usually colorless, yellowish or slightly brownish, rarely blue-green to dark blue.

Main photo : Roedderite from Sierra de las Cabras, Spain © Juan Miguel Segura

Roedderite from Caspar Quarry, Ettringe, Germany © Stephan Wolfsried
Roedderite from Caspar Quarry, Ettringe, Germany © Volker Betz
Roedderite from Sierra de las Cabras, Spain © Francisco Antonio Garcia Alacid
Roedderite from Mont Denise, Haute-Loire, France © Serge Lavarde

Roedderite in the World

Roedderite is known in the gneissic xenoliths of leucite tephrites from more than ten volcanoes in the Eifel (Germany), as well as in several meteorites, including that of Indarch (Russia) and Meteor Crater (Arizona).

Roedderite in France

In France, roedderite is known on two volcanoes of Velay (Haute Loire) : Mont Denise and Bizac, as well as at Puy de Vivanson (Puy-de-Dôme).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 5 to 6
Density : 2.6
Fracture : Undetermined
Streak : White

TP : Translucent to transparent
RI : 1.536 to 1.547
Birefringence : 0.001
Optical character : Uniaxial +
Pleochroism : Visible
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None