metamorphic

Garnet-bearing metamorphic rock, likely schist or gneiss

Biotite–garnet schist/gneiss; dark minerals likely biotite and graphite or amphibole, with quartz and feldspar

AI-generated identification · may be incorrect

Coarse, irregular specimen with black, glittery foliated material, pinkish-brown matrix, and pale quartz/feldspar patches. Likely Mohs hardness 2.5–7 depending on mineral; mica has pearly luster and perfect cleavage, while quartz is glassy and garnet is typically hard, vitreous, and cleavage-free.

Identified September 21, 2026More metamorphic →

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At a glance

Common name: Garnet-bearing metamorphic rock, likely schist or gneiss
Scientific name: Biotite–garnet schist/gneiss; dark minerals likely biotite and graphite or amphibole, with quartz and feldspar
Category: metamorphic
Identified: September 21, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$100 or more if it contains large, well-formed garnets or unusually attractive mineral contrast.

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 shale or another clay-rich sediment was buried and subjected to regional metamorphism, producing foliation and recrystallized minerals. Such rocks commonly formed during Precambrian to Paleozoic mountain-building events, though the exact age cannot be determined from the image.

Uses & applications

Primarily a teaching and collecting specimen; massive varieties may be used as decorative stone or aggregate, but foliated material is generally unsuitable for major construction applications.

Geological facts

The bright reflective surfaces may be mica flakes, while reddish grains could be garnet or iron-oxide staining. A magnet, streak test, and close inspection of individual crystals would improve identification.

Field identification & locations

Common in metamorphic belts worldwide, including the Appalachians, New England, Colorado, and many Precambrian shields. Look for planar foliation, mica sparkle, quartz veins, and garnet crystals; avoid assuming the dark material is graphite without testing.