metamorphic

Likely pyrite-bearing metamorphic rock

Quartz–mica schist or gneiss with disseminated pyrite (FeS₂)

AI-generated identification · may be incorrect

Hardness is approximately 6–7 for quartz and 6–6.5 for pyrite; the specimen is gray-brown with brassy metallic grains and a granular, weakly foliated texture. Pyrite is cubic in crystals when well formed, while the surrounding rock commonly contains quartz, mica, and feldspar;…

Identified September 12, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when clay-rich sediment or igneous rock was buried, heated, and compressed during mountain building; pyrite crystallized in the metamorphic assemblage. Its exact geological age cannot be determined from the photograph.

Uses & applications

Mostly a collector specimen; pyrite may be mined for sulfur and historically for iron, while the host rock can be used as decorative stone but is not typically construction-grade.

Geological facts

The brassy metallic material is likely pyrite, commonly called “fool’s gold,” though the rock may also contain chalcopyrite. Pyrite can tarnish or oxidize in humid conditions, producing acidic minerals.

Field identification & locations

Look for metallic brassy grains, gray quartz-rich matrix, and possible foliation; pyrite leaves a dark greenish-black streak, unlike gold’s yellow streak. Common settings include hydrothermal veins and metamorphic belts worldwide.