Porphyritic biotite quartz syenite in central Jefferson dome in Mt. Washington quadrangle

Porphyritic biotite quartz syenite in central Jefferson dome in Mt. Washington quadrangle.
State New Hampshire
Name Porphyritic biotite quartz syenite in central Jefferson dome in Mt. Washington quadrangle
Geologic age Late Ordovician
Lithologic constituents
Major
Igneous > Plutonic > Syenitic > Quartz-syenite (Pluton)porphyritic biotite quartz syenite
Comments Part of the Oliverian Plutonic Suite (Late Ordovician) - Pink, weakly to moderately foliated, locally porphyritic biotite granitoids found in mantled gneiss domes. Mafic varieties contain hornblends. Variably metamorphosed up to amphibolite facies.
References
NGMDB product
Counties Coos