metamorphic
Banded metamorphic rock, likely mica schist or gneiss
Mica schist/gneiss, chiefly quartz, feldspar, biotite and muscovite
AI-generated identification · may be incorrectMohs hardness about 2–7 depending on mineral; strongly foliated with brown, gray, reddish and cream bands, silky to dull luster, and mica-rich layers that split along foliation. The specimen appears fine- to medium-grained and irregularly weathered.
Identified More metamorphic →
Explore Banded metamorphic rock, likely mica schist or gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness about 2–7 depending on mineral; strongly foliated with brown, gray, reddish and cream bands, silky to dull luster, and mica-rich layers that split along foliation. The specimen appears fine- to medium-grained and irregularly weathered.
Formation & geological history
Formed when shale or another quartz-feldspar-rich sedimentary/protolith was buried and subjected to elevated heat and pressure, producing aligned mica and compositional banding. Such rocks commonly formed during ancient mountain-building events, often hundreds of millions to billions of years ago.
Uses & applications
Used locally as dimension stone, decorative landscaping rock, wall stone and aggregate; attractive polished pieces may be sold as geological specimens, but this example is not typically a gemstone.
Geological facts
The alternating light and dark bands record metamorphic segregation and deformation. Abundant shiny, platy mica and pronounced foliation favor schist; thicker, compositionally distinct bands would favor gneiss.
Field identification & locations
Identify it by its planar mineral alignment, banding, and tendency to break along foliation; a fresh surface may reveal sparkling mica. Common in exposed mountain belts and Precambrian terrains worldwide, including the Appalachians, Alps and Canadian Shield.
More like this
