sedimentary or igneous

Rounded gray pebble, likely limestone or fine-grained basalt

Indeterminate from image; possible micritic limestone (calcite, CaCO₃) or basalt (plagioclase, pyroxene, minor oxides)

AI-generated identification · may be incorrect

Smooth, water-worn, fine-grained gray surface with dark mottling and dull to slightly granular luster; hardness likely about 3 for limestone or 6 for basalt. No visible crystals, cleavage, or layering; specific gravity cannot be determined visually.

Identified August 19, 2026More sedimentary or igneous →

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At a glance

Common name: Rounded gray pebble, likely limestone or fine-grained basalt
Scientific name: Indeterminate from image; possible micritic limestone (calcite, CaCO₃) or basalt (plagioclase, pyroxene, minor oxides)
Category: sedimentary or igneous
Identified: August 19, 2026
Method: Standard

AI Estimated Value

Generally $0–$5 as an ordinary pebble; up to roughly $5–$20 if unusually attractive, polished, or locally significant.

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

Probably a naturally weathered and transported pebble formed in a stream, beach, or glacial deposit; its geological age and source rock are indeterminate from the photograph.

Uses & applications

Common pebbles have little commercial value, though suitable pieces may be used decoratively, in landscaping, or for craft polishing.

Geological facts

The dark patches may reflect iron/manganese staining, weathering, or inclusions rather than a distinct rock type.

Field identification & locations

Test with a steel nail and apply dilute hydrochloric acid or vinegar to a fresh surface: fizzing suggests calcite-rich limestone; strong resistance and a uniformly fine crystalline texture favor basalt. Common worldwide in river gravels and glacial deposits.

Other sedimentary or igneous specimens

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Pyrite

Iron Sulfide (FeS2)

mineral

Likely serpentinite (serpentine-rich rock)

Serpentinite, composed mainly of serpentine-group minerals (e.g., antigorite, lizardite, or chrysotile)

metamorphic

Iron-stained milky quartz

Quartz (SiO₂), with iron-oxide staining

mineral

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Sedimentary rock

Quartz Geode

Silicon Dioxide (SiO2) within Sedimentary or Igneous host

mineral

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary or Igneous Matrix

igneous