Ordovician? granitic gneiss

(Including local terms Ansonia, Mine Hill, "Tyler Lake," "Siscowit") - White, light-gray, buff, or pink, generally foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and biotite, and locally garnet or sillimanite. Commonly contains numerous inclusions or layers of mica schist and gneiss.
State Connecticut
Name Ordovician? granitic gneiss
Geologic age Middle Ordovician?
Lithologic constituents
Major
Metamorphic > GneissWhite, light-gray, buff, or pink, generally foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and biotite, and locally garnet or sillimanite.
Minor
Metamorphic > Schist > Mica-schistCommonly contains numerous inclusions or layers of mica schist.
Comments Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; including local terms Ansonia, Mine Hill, "Tyler Lake," "Siscowit" . Same as Og
References

Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 1:125,000.

NGMDB product
Counties Fairfield