PIGEONITE

    Class : Silicates
    Subclass : Inosilicates
    Crystal system : Monoclinic
    Chemistry : (Mg,Fe,Ca)2Si2O6
    Rarity : Uncommon

Pigeonite is a clinopyroxene poor in calcium (7% Cao compared to more than 19% in diopside and augite) whose structure is close to that of diopside. It is a constituent of lavas having undergone rapid cooling, sometimes an accessory mineral of anorthosites and alkaline rocks. Its name comes from its location of discovery : Pigeon in Minnesota (USA). It is sometimes found in small brown to black crystals not exceeding one centimeter, but appears mainly in xenomorphic grains. It is exceptionally used as a gemstone.

Main photo : Pigeonite from Syros Island, Greece © David J. Eicher

Pigeonite in the World

Pigeonite is known in many places on the planet, notably in the lavas of Scotland, and in the diabase dykes of Minnesota and New Jersey. Significant masses are included in the Palabora carbonatite (South Africa). Finally, pigeonite was brought back in several lunar expeditions and seems to be a common component of the basalts of our satellite as well as certain meteorites.

Pigeonite in France

In France, pigeonite is known in a number of meteorites, as well as at Puy Gonnard (Puy-de-Dôme).

Twinning

Twins are common on {100} or {001}, single or multiple. Lamellar exsolutions of orthopyroxene are possible.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 6
Density : 3.30 to 3.46
Fracture : Irregular
Streak : Gray-white

TP : Translucent to opaque
RI : 1.683 to 1.752
Birefringence : 0.021 to 0.030
Optical character : Biaxial +
Pleochroism : None
Fluorescence : None

Solubility : Insoluble

Magnetism : ParamagneticRadioactivity : None