Fassaite

Fassaite is a variety of augite with a very low iron content, Ca(Mg,Fe,Al)(Si,Al)2O6.[1] 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)
Identification
Colorlight-dark green, black
Crystal habitprismatic, short, plane
Mohs scale hardness6
Streakgreenish-white
Specific gravity2.9-3.3

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.[2]

References
  1. Mindat
  2. Simon, S. B. and L. Grossman, A comparative study of melilite and fassaite in Types B1 and B2 refractory inclusions, Geochimica et Cosmochimica Acta 70 (2006) 780–798
  • Schumann, Walter (1991). Mineralien aus aller Welt. BLV Bestimmungsbuch (2 ed.). p. 223. ISBN 3-405-14003-X.


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