metamorphic

Weathered, foliated metamorphic rock (likely gneiss)

Quartz–feldspar–mica gneiss; exact identification requires closer examination

AI-generated identification · may be incorrect

Coarse, pale gray to tan, with darker mineral flecks and weakly visible banding or foliation. Likely contains quartz, feldspar, and mica; typical gneiss hardness is about 6–7 Mohs, with no consistent cleavage at the rock scale.

Identified October 14, 2026More metamorphic →

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At a glance

Common name: Weathered, foliated metamorphic rock (likely gneiss)
Scientific name: Quartz–feldspar–mica gneiss; exact identification requires closer examination
Category: metamorphic
Identified: October 14, 2026
Method: Standard

AI Estimated Value

About $0–$10 for an ordinary hand specimen; more if provenance, quality, or distinctive appearance adds collecting interest.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms when pre-existing rocks undergo high-temperature, high-pressure metamorphism, commonly deep in continental crust. Its age cannot be determined from appearance alone.

Uses & applications

Gneiss is used as dimension stone, crushed aggregate, and landscaping stone; attractive pieces may be collected or polished.

Geological facts

Gneiss commonly develops alternating light and dark mineral bands, though weathering can obscure them.

Field identification & locations

Look for coarse interlocking grains and compositional banding; distinguish it from granite by foliation. Gneiss occurs widely in ancient continental mountain belts and exposed basement rocks.