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Hoosac Formation

Hoosac Formation - Rusty-brown to dark-gray, albite-spotted muscovite-biotite schist or gneiss, with interlayered black garnet-biotite-albite-quartz schist near base; interfingers with Dalton Formation.
State Massachusetts
Name Hoosac Formation
Geologic age Lower Cambrian and Proterozoic Z
Comments Part of Taconic-Berkshire Zone (Ordovician and Older Rocks)
Primary rock type mica schist
Secondary rock type gneiss
Other rock types schist
Lithologic constituents
Major
Metamorphic > Schist > Mica-schistalbite-spotted muscovite-biotite schist or gneiss, with interlayered black garnet-biotite-albite-quartz schist near base
Minor
Metamorphic > Gneissalbite-spotted muscovite-biotite schist or gneiss
Map references
Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
Unit references
Zen, E-An (ed.), Goldsmith, R. (comp.), Ratcliffe, N.M. (comp.), Robinson, P. (comp.), Stanley, R.S. (comp.), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000.
Counties Berkshire