ANCYLITE

    Class : Carbonates, Nitrates, Borates
    Subclass : Hydrated carbonates
    Crystal System : Orthorhombic
    Chemistry : SrCe(CO3)2(OH) H2O
    Rarity : Fairly common


Ancylite appears mainly in nepheline syenites, carbonatites, and generally in alkaline rocks and their pegmatites ; it is particularly common in the calcite veinlets that run through these rocks. Its name comes from the Greek ankilos (curved), recalling the rounded crystalline forms that this mineral presents. Its colors are variable (gray to pale yellow, pinkish, sometimes brown) and it forms small stubby to elongated pseudo-octahedral or prismatic crystals with curved and dull faces, frequently associated in groups.

Ancylite from Poudrette Quarry, Quebec, Canada
© Stephan Wolfsried
Ancylite from Poudrette Quarry, Quebec, Canada
© Stephan Wolfsried
Ancylite from Poudrette Quarry, Quebec, Canada
© Stephan Wolfsried
Brown ancylite of Almenningen Quarry, Larvik, Norway
© OT Ljostad

Ancylite in the World

Ancylite is known from the alkaline massifs of Mont St-Hilaire (Canada), Langeundsfjord (Norway) and Khibiny (Russia). But the best samples come from the Ilimaussaq complex near Narssaq (Greenland) where crystals were discovered in the geodes of sodalite syenite pegmatites, and from the Bearpaw Mountains (Montana) which provided decimetric masses of this mineral.
 
Main photo : Ancylite from Poudrette Quarry, Quebec, Canada - © Gianfranco Ciccolini

Ancylite in France

Anapaite is not reported in the French underground.

Twinning

No twin report for this mineral species.

Fakes and treatments

No fake reported for this species.


Hardness : 4 to 4.5
Density : 3.95
Fracture : Irregular
Trace : White


TP : Translucent to transparent
RI : 1.625 to 1.735
Birefringence : 0.110
Optical character : Biaxial -
Pleochroism : Not visible
Fluorescence : None

Solubility : Acids

Magnetism : None
Radioactivity : None