metamorphic

Likely schist or foliated metamorphic rock

Mica schist, possibly amphibole-bearing; composition likely quartz, feldspar, biotite and/or hornblende

AI-generated identification · may be incorrect

Dark gray-black, coarse and weakly shiny with elongated mineral alignment; typical hardness 2–7 depending on mica versus quartz, with micaceous sparkle and foliated texture. Specific gravity is commonly about 2.7–3.3; no reliable cleavage or crystal form is visible at specimen scale.

Identified September 10, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or volcanic protolith was subjected to elevated temperature and directed pressure during regional metamorphism, commonly during mountain building. Its exact geological age cannot be determined from the photograph and may range from Precambrian to younger.

Uses & applications

Used locally as decorative stone, landscaping material, aggregate, and occasionally dimension stone; attractive mica-rich pieces are collected but are rarely gem-grade.

Geological facts

The aligned minerals record the direction of tectonic compression and can split along foliation. A fresh surface may reveal bright mica flakes or distinct quartz-rich bands.

Field identification & locations

Common in metamorphic belts worldwide, including the Appalachians, New England, Alps, Himalaya, and Rocky Mountains. Look for planar layering, sparkly mica, and hardness variation; a hand lens and streak, hardness, or acid tests would improve identification.