Biotite and/or hornblende granite gneiss

Locally pyroxenic; commonly with subordinate leucogranitic gneiss, biotite-quartz-plagioclase gneiss, other metasedimentary rocks, amphibolite, migmatite. Amphibolite with porphyroblasts of K-feldspar locally prominent in northwest Adirondacks. Overprint signifies inequigranular texture or phacoidal structure. In northwest Adirondacks, grades into Yphg.
State New York
Name Biotite and/or hornblende granite gneiss
Geologic age Middle Proterozoic
Lithologic constituents
Major
Metamorphic > GneissBiotite and/or hornblende granite gneiss - locally pyroxenic; commonly with subordinate leucogranitic gneiss, biotite-quartz-plagioclase gneiss.
Minor
Metamorphic > Metasedimentarymetasedimentary rocks
Incidental
Metamorphic > Migmatite
Metamorphic > Amphibolite
References

Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250,000.

NGMDB product
Counties Essex - Franklin - Hamilton - Herkimer - Jefferson - Lewis - Saint Lawrence - Warren - Washington