Ratlum Mountain Schist plus Amphibolite unit [in Ratlum Mountain Schist]

Ratlum Mountain Schist - Gray, medium-grained, interlayered schist and granofels, composed of quartz, oligoclase, muscovite (in the schist), biotite, and garnet, also staurolite and kyanite in the schist. Numerous layers and lenses of amphibolite; also some of quartz-spessartine (coticule) and calc-silicate rock. Amphibolite unit [in Ratlum Mountain Schist] (Lower? Ordovician) - Black or mottled, generally massive amphibolite and hornblende gneiss, composed of hornblende and andesine, commonly with minor quartz and magnetite, and locally with garnet, biotite, and epidote.
State Connecticut
Name Ratlum Mountain Schist plus Amphibolite unit [in Ratlum Mountain Schist]
Geologic age Lower Ordovician
Lithologic constituents
Major
Metamorphic > Granoblastic > GranofelsRatlum Mountain Schist - Gray, medium-grained, interlayered schist and granofels, composed of quartz, oligoclase, muscovite (in the schist), biotite, and garnet, also staurolite and kyanite in the schist.
Metamorphic > SchistRatlum Mountain Schist - Gray, medium-grained, interlayered schist and granofels, composed of quartz, oligoclase, muscovite (in the schist), biotite, and garnet, also staurolite and kyanite in the schist.
Metamorphic > AmphiboliteRatlum Mountain Schist - Numerous layers and lenses of amphibolite. Amphibolite unit [in Ratlum Mountain Schist] (Lower? Ordovician) - Black or mottled, generally massive amphibolite and hornblende gneiss, composed of hornblende and andesine, commonly with minor quartz and magnetite, and locally with garnet, biotite, and epidote.
Minor
Metamorphic > Gneiss > Hornblende-gneissAmphibolite unit [in Ratlum Mountain Schist] (Lower? Ordovician) - Black or mottled, generally massive amphibolite and hornblende gneiss, composed of hornblende and andesine, commonly with minor quartz and magnetite, and locally with garnet, biotite, and epidote.
Incidental
Metamorphic > Metasedimentary > Calc-silicate-rockRatlum Mountain Schist - calc-silicate rock
Comments Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Equivalents of Savoy Schist of Massachusetts (Emerson, 1898, 1917) and of Moretown Formation of Vermont and Massachusetts (Bedrock Geologic Map of Massachusetts, Zen and others, 1983) (includes Golden Hill and Ratlum Mountain Schists) (Lower? Ordovician). Units are described seperately on printed map; combined in digital map.
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 Litchfield