Banded metamorphic rock, likely mica schist

Typically Mohs 2–7 depending on minerals; gray, brown, and silvery bands with vitreous to pearly luster. Foliated, with platy mica grains and pronounced schistosity; cleavage follows mica layers.

Forms when shale or other clay-rich sediment is subjected to regional heat and pressure, commonly during mountain building. Individual specimens may range from Paleozoic to Precambrian in age; age cannot be determined from the photo.

Used locally as decorative stone, landscaping material, and occasionally building veneer; attractive foliated pieces are collected. It is generally unsuitable for heavy construction because it splits along foliation.

The layered appearance reflects metamorphic segregation and alignment of mica minerals, not ordinary sedimentary bedding. Dark bands may contain biotite or graphite, while lighter bands commonly contain quartz and feldspar.

Identify by its glittering mica flakes, planar foliation, and tendency to split into thin irregular slabs; a hand lens and streak/hardness tests help distinguish it from banded gneiss. Common in metamorphic mountain belts worldwide, including New England, the Appalachians, Scandinavia, and the Himalaya.