Geographic Minerals

Fassaite: Properties and Occurrences

Fassaite: Properties and Occurrences

Fassaite is a variety of augite with a very low iron content, Ca(Mg, Fe, Al)(Si, Al)2O6. It is a mineral consisting of a pale green to a dark green variety of augite. It is named after the Fassa Valley, Italy. It is a dark-green variety of pyroxene, found in the valley of Fassa in Tyrol.

It is thought to be a contact mineral formed at a high temperature on the interface between volcanic rocks and limestone. It is also reported in meteorites.

General Information

  • Category: Mineral
  • Formula: Ca(Mg,Fe,Al)(Si,Al)2O6
  • Crystal system: Monoclinic
  • Crystal class: Prismatic (2/m) (same H-M symbol)

Fig: Fassaite Рvariety of augite


  • Color: light-dark green, black
  • Crystal habit: prismatic, short, plane
  • Mohs scale hardness: 6
  • Streak: greenish-white
  • Specific gravity: 2.9-3.3


Variety of Augite originally described from the Val D’Fassa region in Italy which has a low iron content. This is usually responsible for this variety having a lighter green color and increased translucency then other most Augite.


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