Name:  Sillimanite-Garnet Gneiss

Geologic Name:  Hague Gneiss

Reference:  Alling, H.L., The Adirondack graphite deposits: New York
State Mus. Bull. 199, p. 44-55, 1918.

Microscopic characters: The feldspar constituents are microcline, perthite
and sodic plagioclase, all partially altered to sericite.  Quartz grains
show undulatory extinction.  Biotite, partially altered to chlorite
contains zircon with pleochroic halos.  There are also large poikilitic
garnet crystals, small grains of pyrite, abundant magnetite with
leucoxene coatings and long slender crystals of sillimanite.
Chlorite and calcite also ocur in patches.