||Cordierite and Quartz
Pegmatite in Manhattan Schist
Fairfield County, Connecticut
Cordierite and quartz are the two most abundant minerals in this rock.
They grew together under high temperature and pressure that existed in
the deep roots of the Appalachian mountains during the early stages of
their formation. The orange giraffe is a cordierite crystal that is
speckled with sillimanite needles and dark, grungy patches of sericite
plus iron-oxide. The oxides, sericite, and sillimanite formed when the
temperature dropped as the overlying high mountains were eroded away.
Crossed polarizers with gypsum plate