metamorphic

Schist with sulfide mineralization

Mica schist, likely containing pyrite and/or chalcopyrite; quartz-rich matrix

AI-generated identification · may be incorrect

Dark gray, foliated rock with glittering platy mica and scattered brassy metallic sulfides; white patches are likely quartz or feldspar. Typical hardness is about 2–3 for mica, 6–7 for quartz, and 6–6.5 for pyrite; foliation gives a layered texture and uneven cleavage.

Identified September 8, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or another clay-rich sediment was subjected to regional metamorphism, commonly during mountain building. The sulfides precipitated from hydrothermal fluids or were retained and recrystallized during metamorphism; exact age and locality cannot be determined from the image.

Uses & applications

Used mainly as a decorative or educational specimen; sound schist may be used locally as facing stone, but strong foliation limits structural use. Sulfide-bearing pieces can be attractive to collectors, though they are generally not gem material.

Geological facts

Brassy grains that leave a dark streak and resist a steel blade are likely pyrite; softer, more yellow copper sulfides may indicate chalcopyrite. Sulfide-rich specimens can weather to rusty iron oxides and may generate acidic runoff.

Field identification & locations

Identify it by visible foliation, mica sparkle, and metallic grains; a hand lens, streak test, hardness test, and magnet check help distinguish pyrite from other sulfides. Schist is common in metamorphic belts worldwide, including the Appalachians, Alps, Himalaya, and Precambrian shields.