metamorphic

Coarse-grained metamorphic rock, likely gneiss or schist

Probable biotite-quartz-feldspar gneiss/schist; exact identification requires a fresh surface and tests

AI-generated identification · may be incorrect

Gray-brown, foliated and granular, with visible pale quartz/feldspar and dark mica-like minerals; likely Mohs hardness 6–7 overall, vitreous to dull luster, and moderate to strong planar fabric. Cleavage is mainly within mica layers rather than the whole specimen; specific gravity approximately 2.6–2.8.

Identified September 15, 2026More metamorphic →

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At a glance

Common name: Coarse-grained metamorphic rock, likely gneiss or schist
Scientific name: Probable biotite-quartz-feldspar gneiss/schist; exact identification requires a fresh surface and tests
Category: metamorphic
Identified: September 15, 2026
Method: Standard

AI Estimated Value

About $5–$25 for an ordinary hand specimen; $25–$100 if unusually attractive, large, or locality-documented.

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

Formed when preexisting igneous or sedimentary rock was subjected to elevated temperature and pressure, producing mineral alignment and possible banding. Such rocks commonly formed during Precambrian to Paleozoic mountain-building events, though age cannot be determined visually.

Uses & applications

Used locally as crushed aggregate, dimension stone, landscaping rock, and building facing; attractive polished pieces may be collectible, but this specimen appears ordinary.

Geological facts

The apparent sparkle and layering are consistent with mica-rich metamorphic fabric, while pale granular patches may be quartz or feldspar. A definitive distinction from weathered granite requires examining a broken or freshly cut face.

Field identification & locations

Common in metamorphic terrains and mountain belts worldwide. Look for foliation, aligned mica flakes, and resistance to scratching by steel; dilute acid should produce no reaction unless carbonate minerals are present.