Collinsville Formation

Felsic gneiss containing scattered biotite, magnetite, garnet and hornblende. Local beds of amphibolite.
State Massachusetts
Name Collinsville Formation
Geologic age Middle Ordovician or older
Lithologic constituents
Major
Metamorphic > GneissFelsic gneiss containing scattered biotite, magnetite, garnet and hornblende.
Minor
Metamorphic > Amphibolite
Comments Part of Bronson Hill Zone (Ordovician and Older Rocks)
References
NGMDB product
Counties Franklin