metamorphic

Micaceous schist (likely biotite schist)

Biotite–quartz–feldspar schist; commonly containing muscovite and/or garnet

AI-generated identification · may be incorrect

Medium- to coarse-grained, foliated rock with glittering mica flakes and gray-green to brown coloration; mica gives a pearly to vitreous luster. Hardness is roughly 2.5–3 for mica and 6–7 for quartz/feldspar; schistosity is the dominant texture, with weak cleavage across the rock.

Identified August 31, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or other clay-rich sediment was regionally metamorphosed under elevated temperature and pressure, typically during mountain building. Its exact geological age cannot be determined from the photograph; schists range from Precambrian to Cenozoic.

Uses & applications

Used locally as decorative stone, landscaping rock, and occasionally as low-grade building material; attractive mica-rich pieces are collected but are generally not valuable as gemstones.

Geological facts

The pronounced foliation develops as platy mica minerals align under directed pressure. A streak of glitter does not by itself indicate gold; mica commonly produces the sparkle.

Field identification & locations

Common in metamorphic belts worldwide, including the Appalachians, New England, the Alps, and parts of the western United States. Confirm by examining thin, peelable mica layers and testing for abundant quartz/feldspar; field identification from one photo is provisional.