WÖHLERITE

    Class : Silicates
    Subclass : Sorosilicates
    Crystal system : Monoclinic
    Chemistry : Na2Ca4ZrNb(Si2O7)2(O,F)4
    Rarity : Uncommon to fairly common


Wöhlerite is a complex silicate of silica-undersaturated alkaline rocks, mainly carbonatites, fenites, nepheline syenites and their pegmatites. It was named in honor of the German chemist Friedrich Wöhler, Professor at the University of Göttingen (Germany). Wöhlerite is a yellow to light brown, sometimes gray, mineral that forms prismatic or tabular crystals of rectangular appearance not exceeding 3 cm.

Main photo : Wöhlerite from Torbjørnsås Quarry, Norway © Knut Edvard Larsen

Wöhlerite in the World

This is not a rare mineral : it is known in most of the world's major districts of alkaline massifs. Mont St-Hilaire has given small crystals of 5 mm, as have the nepheline syenite massifs of the Kola Peninsula in Russia (Lovozero, Khibiny). The most beautiful crystals come from the alkaline syenites of southern Finland (Langesundfjord district), they are centimetric. Wöhlerite is also known in carbonatites from Mali and in the nepheline syenites of the Los Islands (Guinea).

Right photo : Wöhlerite from In den Dellen quarries, Eifel, Germany © Volker Betz

Wöhlerite in France

In France, wöhlerite is reported in the nepheline syenite intrusion of Fitou (Aude).

Twinning

Twinning is common on {010}.

Fakes and treatments

No fakes listed for this mineral species.



Hardness : 5.5 to 6
Density : 3.40 to 3.44
Fracture : Irregular
Streak : Light yellow


TP : Translucent to transparent
RI : 1.700 to 1.728
Birefringence : 0,026
Optical character : Biaxial -
Pleochroism : Low
Fluorescence : None


Solubility : -

Magnetism : NoneRadioactivity : None