Layered gneiss

Gray, medium-grained, well-foliated and generally well layered, light and dark, but locally wispy gneiss, composed of quartz and plagioclase, with microcline locally in the light layers and abundant biotite and common hornblende in the dark layers; garnet or epidote locally. Layers and lenses of calc-silicate rock and amphibolite in some areas.
State Connecticut
Name Layered gneiss
Geologic age Proterozoic Y
Lithologic constituents
Major
Metamorphic > GneissGray, medium-grained, well-foliated and generally well layered, light and dark, but locally wispy gneiss, composed of quartz and plagioclase, with microcline locally in the light layers and abundant biotite and common hornblende in the dark layers; garnet or epidote locally.
Incidental
Metamorphic > AmphiboliteLayers and lenses of amphibolite in some areas.
Metamorphic > Metasedimentary > Calc-silicate-rockLayers and lenses of calc-silicate rock in some areas.
Comments Part of Western Uplands; Proto-North American (Continental) Terrane - Proterozoic Massifs - ""Grenville""
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 Hartford - Litchfield