sedimentary

Rounded quartz-rich sandstone pebble

Quartz arenite (sandstone), composition mainly SiO₂ with minor feldspar, mica, and iron-oxide cement

AI-generated identification · may be incorrect

Fine- to medium-grained, gray-brown, dull to subtly sparkling surface, with rounded cobble shape from abrasion. Quartz hardness is about 7 Mohs; sandstone typically has variable hardness, porosity, and weak-to-moderate cementation; no obvious cleavage or visible crystals.

Identified August 17, 2026More sedimentary →

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At a glance

Common name: Rounded quartz-rich sandstone pebble
Scientific name: Quartz arenite (sandstone), composition mainly SiO₂ with minor feldspar, mica, and iron-oxide cement
Category: sedimentary
Identified: August 17, 2026
Method: Standard

AI Estimated Value

Typically $2-$15 for a common natural pebble; up to about $20-$50 if unusually shaped, locality-labeled, fossiliferous, or attractively patterned.

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

Lithified sand deposited in a river, beach, dune, or shallow-marine environment, then rounded by water or transport. Its exact geological age cannot be determined from the image and may range from ancient to modern sedimentary deposits.

Uses & applications

Common sandstone is used for building stone, paving, landscaping, aggregate, and historically carving; this rounded specimen is mainly suitable for collecting or display. It has little jewelry value unless unusually colorful, patterned, or fossil-bearing.

Geological facts

The granular texture and uniform gray-brown color are consistent with quartz-rich sandstone, though a weathered fine-grained metamorphic rock is also possible from an image alone.

Field identification & locations

Look for individual sand grains, gritty texture, and possible effervescence only if carbonate cement is present; a hand lens and streak/fracture tests help distinguish it from quartzite, which is harder and more fused. Sandstone pebbles occur widely in streambeds, beaches, deserts, and glacial deposits.