metamorphic

Dark metamorphic pebble, likely serpentinite or foliated amphibolite

Probable serpentinite (serpentine-group minerals) or amphibolite; exact identification requires testing

AI-generated identification · may be incorrect

Dark gray-green, fine-grained, dull to weakly silky luster, with folded/foliated texture and an irregular lens shape. Estimated Mohs hardness 3–6 depending on composition; cleavage is poor to moderate and specific gravity about 2.6–3.3.

Identified September 10, 2026More metamorphic →

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At a glance

Common name: Dark metamorphic pebble, likely serpentinite or foliated amphibolite
Scientific name: Probable serpentinite (serpentine-group minerals) or amphibolite; exact identification requires testing
Category: metamorphic
Identified: September 10, 2026
Method: Standard

AI Estimated Value

$1–$10 as an unattributed pebble; up to about $10–$30 if locality and mineral identity are confirmed.

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 ultramafic rock was hydrated and metamorphosed (serpentinite), or when basalt was metamorphosed (amphibolite), commonly in tectonic zones and ophiolites. The specimen appears naturally water-worn; its geological age cannot be determined visually.

Uses & applications

Common serpentinite is used as decorative stone, carving material, and occasionally aggregate; amphibolite may be used as crushed stone or dimension stone. This small specimen has limited commercial value.

Geological facts

The surface texture suggests deformation and weathering rather than a glassy igneous rock. A white streak, magnet test, hardness test, and thin-section or Raman/XRF analysis would distinguish serpentinite from amphibolite.

Field identification & locations

Look for green tones, waxy or greasy luster, and softness for serpentinite; amphibolite is typically harder, black-green, and rich in amphibole. Common sources include ophiolite belts and regional metamorphic terrains.