metamorphic

Dark gray metamorphic rock, likely slate or phyllite

Fine-grained foliated pelite; commonly mica- and chlorite-rich, with quartz and feldspar

AI-generated identification · may be incorrect

Typically Mohs 2.5–4; dark gray to greenish gray, dull to silky luster, very fine-grained, and weakly foliated with possible planar splitting. The photograph is insufficient for confident mineral or exact rock identification.

Identified September 11, 2026More metamorphic →

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At a glance

Common name: Dark gray metamorphic rock, likely slate or phyllite
Scientific name: Fine-grained foliated pelite; commonly mica- and chlorite-rich, with quartz and feldspar
Category: metamorphic
Identified: September 11, 2026
Method: Standard

AI Estimated Value

About $1–$10 as an unidentified common hand specimen; $10–$30 if clearly identified, labeled, and from a notable locality.

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 mudstone was subjected to low-grade regional metamorphism during mountain building; ages vary widely depending on its source terrane. Commonly occurs in metamorphic belts near slate and schist zones.

Uses & applications

Used historically for roofing, paving, flooring, and writing surfaces; attractive pieces may be collected, but this small specimen has little commercial value unless provenance or unusual texture is established.

Geological facts

Slate has strong cleavage and breaks into thin plates, whereas phyllite has a satiny sheen and slightly coarser texture. A hand lens and fresh broken surface would help distinguish it from shale or fine-grained basalt.

Field identification & locations

Common in regions such as Wales, the Appalachian Mountains, New England, the Alps, and many other folded mountain belts. Test for layered splitting, lack of visible glassy crystals, and a streak that is generally pale gray rather than metallic.