Biotitic gneiss, schist, and migmatite

Locally contains minor hornblende gneiss, calc-silicate rock, quartzite, and marble. Derived principally from sedimentary rocks
State Colorado
Name Biotitic gneiss, schist, and migmatite
Geologic age Early Proterozoic
Lithologic constituents
Major
Metamorphic > Gneiss > Biotite-gneiss
Metamorphic > Migmatite
Metamorphic > Schist
Minor
Metamorphic > Schist > Calc-silicate-schist
Metamorphic > Gneissmafic gneiss
Metamorphic > Metasedimentary > Metacarbonate > Marble
References

Tweto, Ogden, 1979, Geologic Map of Colorado: U.S. Geological Survey Special Geologic Map, scale 1:500,000.

NGMDB product
Counties Boulder - Chaffee - Clear Creek - Costilla - Delta - Douglas - Eagle - El Paso - Fremont - Garfield - Gilpin - Grand - Gunnison - Jackson - Jefferson - Lake - Larimer - Mesa - Montrose - Park - Pitkin - Routt - Saguache - Summit - Teller