Fassaite is a variety of

augite Augite is a common rock-forming pyroxene mineral with formula . The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees. Characteristics Augite is a solid solution in the pyroxene group ...

with a very low iron content, .Mindat
/ref> It is named after the Fassa Valley,

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

. 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

meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object en ...

s.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
/ref>

References

* Inosilicates Monoclinic minerals Minerals in space group 15 {{Silicate-mineral-stub