WELOGANITE

    Class : Carbonates, nitrates, borates
    Subclass : Hydrated carbonates
    Crystal system : Monoclinic
    Chemistry : Sr3Na2Zr(CO3)6 3H2O
    Rarity : Very rare

Weloganite is an extremely rare strontium-zirconium carbonate that occurs in carbonatite intrusions in limestones where it is associated with calcite, barite, and zircon. It was named in honor of Sir Edmond Logan, first director of the Geological Survey of Canada. Weloganite forms pseudohexagonal prismatic crystals that are often polysynthetic, colorless to white or faintly colored yellow, blue, green, or gray.

Main photo : Weloganite from Francon Quarry, Montreal, Quebec, Canada © Nadya Georgieva

Weloganite and quartz from Francon Quarry, Quebec, Canada © Michael C. Roarke
Bicolor weloganite from Francon Quarry, Canada © Eugene & Sharon Cisneros
Weloganite from Francon Quarry, Montreal, Quebec, Canada © Nadya Georgieva
5 cm weloganite from Francon Quarry, Montreal, Quebec, Canada © Rock Currier

Weloganite in the World

The best weloganite crystals come from the Francon quarry in the heart of Montreal (Canada), they measure up to 6.4 cm in length. It is also reported at Mont Saint-Hilaire.

Weloganite in France

Weloganite is not present in the French underground.

Twinning

Twinning on [103] that can be repeated at 120° are known.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3.5
Density : 3.20 to 3.22
Fracture : Conchoidal
Streak : White

TP : Translucent
RI : 1.558 to 1.646
Birefringence : 0.082
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : NoneRadioactivity : None