TRIMOUNSITE

    Class : Silicates
    Subclass : Nesosilicates
    Crystal system : Monoclinic
    Chemistry : Y2Ti2SiO9
    Rarity : Very rare


Trimounsite is a very rare yttrium-titanium silicate that occurs in the company of other rare earth minerals in hydrothermalized dolomite geodes. Its name comes from its discovery location : the large talc deposit of Trimouns (Ariège, France). Trimounsite forms acicular crystals or flattened rods up to 5 mm, elongated along [001] and translucent, with adamantine luster, colorless to pale brown. It is difficult to distinguish from allanite without laboratory analysis.

Main photo : Tridymite from Emmelberg, Eifel, Germany © Jean-Paul Fayard

Tridymite in France and in the World

Trimounsite is only known in the Trimouns talc deposit (Ariège, France).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.



Hardness : 7
Density : 5
Fracture : Undetermined
Streak : White


TP : Translucent to transparent
RI : 2.100
Birefringence : -
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None


Solubility : Insoluble

Magnetism : NoneRadioactivity : None