metamorphic

Weathered quartz-rich metamorphic rock (probable quartzite or gneiss fragment)

Quartzite–gneiss type specimen; chiefly SiO₂ (quartz) with feldspar, mica, and iron-oxide staining

AI-generated identification · may be incorrect

Hardness approximately 6.5–7; mottled brown, gray, black, and cream with a dull to locally vitreous luster. Irregular granular texture and no obvious cleavage; iron oxides produce the rusty patches.

Identified September 5, 2026More metamorphic →

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At a glance

Common name: Weathered quartz-rich metamorphic rock (probable quartzite or gneiss fragment)
Scientific name: Quartzite–gneiss type specimen; chiefly SiO₂ (quartz) with feldspar, mica, and iron-oxide staining
Category: metamorphic
Identified: September 5, 2026
Method: Standard

AI Estimated Value

About $1–$10 as an ordinary unidentified specimen; $10–$30 if attractive, locality-labeled, or educationally prepared.

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

Likely formed when quartz-rich sandstone or felsic rock was subjected to heat and pressure, then later weathered and rounded in transport; exact age and locality cannot be determined from the photograph.

Uses & applications

Primarily a field or teaching specimen; quartzite may be used as aggregate, building stone, or decorative material, while gneiss is used for countertops and construction.

Geological facts

The dark and rusty areas may represent biotite, amphibole, magnetite, or limonite rather than a single defining mineral. A glassy quartz-rich fracture and resistance to scratching are useful diagnostic clues.

Field identification & locations

Common in metamorphic terrains, stream gravels, glacial deposits, and eroded mountain regions. Test fresh surfaces: it should scratch ordinary glass, show no acid reaction, and reveal interlocking quartz grains; precise identification requires a fresh cut surface or thin section.