Collinsville Formation

Interlayered amphibolite and felsic gneiss in beds less than 1 m thick. Local, coarse-grained magnetite-hornblende gneiss.
State Massachusetts
Name Collinsville Formation
Geologic age Middle Ordovician or older
Lithologic constituents
Major
Metamorphic > GneissInterlayered amphibolite and felsic gneiss in beds less than 1 m thick; local, coarse-grained magnetite-hornblende gneiss.
Metamorphic > AmphiboliteInterlayered amphibolite and felsic gneiss in beds less than 1 m thick.
Comments Part of Bronson Hill Zone (Ordovician and Older Rocks)
References
NGMDB product
Counties Franklin