Rock Identifier
Rounded river cobble, likely weathered volcanic or metamorphic rock (Indeterminate from photograph; possible basaltic-andesite, rhyolite, or quartz-rich metamorphic lithology) — igneous or metamorphic
igneous or metamorphic

Rounded river cobble, likely weathered volcanic or metamorphic rock

Indeterminate from photograph; possible basaltic-andesite, rhyolite, or quartz-rich metamorphic lithology

AI-generated identification · may be incorrect

Smooth, water-worn, fine-grained pebble with muted pink-tan and gray-green coloration, dull to faintly earthy luster, and no visible crystals or cleavage. Estimated Mohs hardness 5–7; specific gravity cannot be determined visually.

Identified More igneous or metamorphic →
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Physical properties

Smooth, water-worn, fine-grained pebble with muted pink-tan and gray-green coloration, dull to faintly earthy luster, and no visible crystals or cleavage. Estimated Mohs hardness 5–7; specific gravity cannot be determined visually.

Formation & geological history

Likely formed as a coherent bedrock fragment, then rounded by prolonged stream or beach abrasion; its precise geological age and parent rock are unknown without locality and testing.

Uses & applications

Usually collected as a natural specimen, landscaping stone, or craft material; it has little industrial or jewelry value unless laboratory examination reveals an attractive or unusual lithology.

Geological facts

The rounded shape indicates transport and abrasion rather than its original formation. A streak test, hardness test, acid test, and fresh broken surface would substantially improve identification.

Field identification & locations

Commonly found in riverbeds, beaches, and glacial deposits. Inspect a fresh surface for quartz grains, feldspar, vesicles, layering, or sparkly mica; avoid destructive tests if it is a valued specimen.

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