Fassaite

Fassaite is a variety of augite with a very low iron content, Ca(Mg,Fe,Al)(Si,Al)2O6. It is named after the Fassa Valley, Italy.

Fassaite
Fassaite from Val di Fassa
General
CategoryMineral
Formula
(repeating unit)
Ca(Mg,Fe,Al)(Si,Al)2O6
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/c (no. 15)
Identification
Colorlight-dark green, black
Crystal habitprismatic, short, plane
Mohs scale hardness6
Streakgreenish-white
Specific gravity2.9-3.3
References

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

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