igneous

Granite (likely biotite granite or granodiorite)

Coarse-grained felsic intrusive rock composed mainly of quartz, feldspar, and mica; approximate composition: SiO₂-rich, with variable K-feldspar/plagioclase and biotite.

AI-generated identification · may be incorrect

Gray, granular texture with visible interlocking crystals and dark mica flakes; typically Mohs 6–7, vitreous quartz luster, no consistent cleavage as a rock, and specific gravity about 2.6–2.8.

Identified September 2, 2026More igneous →

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At a glance

Common name: Granite (likely biotite granite or granodiorite)
Scientific name: Coarse-grained felsic intrusive rock composed mainly of quartz, feldspar, and mica; approximate composition: SiO₂-rich, with variable K-feldspar/plagioclase and biotite.
Category: igneous
Identified: September 2, 2026
Method: Standard

AI Estimated Value

About $1–$10 for a common loose specimen; attractive polished or locality-labeled pieces may sell for $10–$30.

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

Gray, granular texture with visible interlocking crystals and dark mica flakes; typically Mohs 6–7, vitreous quartz luster, no consistent cleavage as a rock, and specific gravity about 2.6–2.8.

Formation & geological history

Formed when silica-rich magma cooled slowly deep underground, allowing large crystals to grow; commonly Precambrian to Phanerozoic in age, depending on locality.

Uses & applications

Widely used as dimension stone, countertops, monuments, aggregate, and building material; unexceptional hand specimens have little commercial or jewelry value.

Geological facts

The specimen’s rounded shape suggests natural weathering or tumbling, while its granular appearance is characteristic of plutonic rocks rather than volcanic rocks.

Field identification & locations

Identify it by visible quartz, light and dark feldspar, and black biotite in a coarse interlocking texture; common worldwide in continental mountain belts and exposed plutons. A precise name requires thin-section or mineral testing.