Fassaite Explained

Fassaite
System:	Monoclinic
Class:	Prismatic (2/m) (same H-M symbol)
Symmetry:	C2/c (no. 15)
Color:	light-dark green, black
Habit:	prismatic, short, plane
Mohs:	6
Streak:	greenish-white
Gravity:	2.9-3.3
References:	^[1]

Fassaite is a variety of augite with a very low iron content, .^[2] It is named after the Fassa Valley, Italy.

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.^[3]

References

• Book: Schumann, Walter . BLV Bestimmungsbuch . Mineralien aus aller Welt . 2 . 1991 . 3-405-14003-X . 223 .

Notes and References

1. Dowty . E. . Clark . J.R. . American Mineralogist . 58 . 1973 . 230–242 . Crystal structure refinement and optical properties of a Ti3+ fassaite from the Allende Meteorite . 1973AmMin..58..230D . 30 December 2020.
2. http://www.mindat.org/min-11019.html Mindat
3. http://geosci.uchicago.edu/~grossman/Comparative_study_mel,_fass.pdf 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