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
Metamorphic > GneissBiotite and/or hornblende granite gneiss, leucogranitic gneiss, biotite-quartz-plagioclase gneiss
Metamorphic > Metasedimentarymetasedimentary rocks
Metamorphic > Amphibolite
Metamorphic > Migmatite
Comments Printed map does not contain a unit named 'hbgo'; only a unit named 'hbg' and mentions that 'overprint signifies inequigranular texture or phacoidal structure'. Overprint means that a different pattern is used over the color of unit 'hbg'. The digital version of the map has separated this unit out into a new unit and called it 'hbgo', so I have included it here.

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 Herkimer - Lewis