Greylock Schist

Light-green to gray, white albite-spotted phyllite and interbedded blue-quartz metagraywacke, salmon-pink dolostone, and blue-quartz conglomerate. Minor interbeds of black and white albite-spotted phyllite resembles Hoosac (CAZhga).
State Massachusetts
Name Greylock Schist
Geologic age Lower Cambrian and Proterozoic Z
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Phyllitealbite-spotted phyllite
Minor
Metamorphic > Metasedimentary > Metaclastic > Metasandstone > Metagraywackeinterbedded blue-quartz metagraywacke
Sedimentary > Carbonate > Dolostone
Sedimentary > Clastic > Conglomerateblue-quartz conglomerate
Incidental
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Comments Part of Taconic-Berkshire Zone (Ordovician and Older Rocks); in the Taconic Allochthon. Secondary unit description from USGS Geologic Names lexicon (ref MA024): Used as Greylock Schist of Proterozoic Z and Early Cambrian age. Divided into two informal unit. Lowermost unit consists of light-green to gray, white albite-spotted phyllite and interbedded blue-quartz metagraywacke, salmon-pink dolostone, and blue-quartz conglomerate; contains minor interbeds of black and white albite-spotted phyllite resembling part of Hoosac Formation. Uppermost part consists of soft, lustrous green phyllite with minor beds of green quartzite and well-laminated, gray, dolomitic phyllite; resembles parts of Hoosac or Nassau Formations.
References
NGMDB product
Counties Berkshire