Collinsville Formation

Plagioclase gneiss and minor amphibolite.
State Massachusetts
Name Collinsville Formation
Geologic age Middle Ordovician or older
Lithologic constituents
Major
Metamorphic > Gneissplagioclase gneiss
Minor
Metamorphic > Amphibolite
Comments Part of Bronson Hill Zone (Ordovician and Older Rocks)
References
NGMDB product
Counties Hampden - Hampshire