TROILITE

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Trigonal
    Chemistry : FeS
    Rarity : Rare

Troilite is a rare iron sulfide. It is essentially an extraterrestrial mineral : it is known almost exclusively in meteorites where it occurs either as rounded nodules in iron meteorites or as regular grains in chondrites. It accompanies chromite, graphite and various phosphates and silicates. Terrestrial troilite is known only in a serpentinite and in mafic stratified complexes. It was named in honor of Dominico Troili who discovered the mineral in 1766. Troilite is brownish gray in color, quickly tarnishing to bronze-brown; its appearance is reminiscent of pyrrhotite.

Main photo : Troilite from Alta Mine, Crescent City, California, USA © Rolf Luetcke

Troilite in the World

Troilite is known from the Crescent City serpentinite (California) and from the Sally Mallay ultrabasic layered complex (Australia) where it is associated with pyrrhotite, cubanite, pentlandite and other magmatic sulfides. It is also known from the native iron site of controversial origin at Disko (Greenland).

Troilite in France

In France, troilite is present in meteorites that have fallen on the territory.

Twinning

Twinning is known but not visible to the eye.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3.5 to 4.5
Density : 4.67 to 4.79
Fracture : Irregular to sub-conchoidal
Streak : Brown-black

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None