sedimentary

Conglomerate (likely polymictic conglomerate)

Clastic sedimentary rock composed of rounded lithic and mineral clasts in a finer matrix; commonly quartz, feldspar, chert, and volcanic fragments cemented by silica, calcite, or iron oxides

AI-generated identification · may be incorrect

Typically hard, gray to brown, with rounded pebble-sized clasts and a granular texture; individual grains are usually Mohs 6–7 (quartz-rich), while whole-rock hardness varies. Non-cleavage, earthy to dull luster, highly variable porosity and specific gravity (~2.2–2.7).

Identified September 10, 2026More sedimentary →

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At a glance

Common name: Conglomerate (likely polymictic conglomerate)
Scientific name: Clastic sedimentary rock composed of rounded lithic and mineral clasts in a finer matrix; commonly quartz, feldspar, chert, and volcanic fragments cemented by silica, calcite, or iron oxides
Category: sedimentary
Identified: September 10, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small common specimen; $30–$100+ for unusually colorful, polished, or locality-documented pieces.

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

Forms when water-rounded gravel and sand accumulate in rivers, alluvial fans, beaches, or submarine channels, then lithify by compaction and cementation. Age cannot be determined from the image; conglomerates range from Precambrian to modern.

Uses & applications

Used locally as dimension stone, aggregate, landscaping rock, and educational specimens; attractive polished pieces may be decorative but are generally not gem-grade.

Geological facts

The rounded clasts indicate transport before burial, unlike angular-clast breccia. Iron-oxide staining likely produces the orange-brown banding.

Field identification & locations

Identify by visible rounded pebbles set in a cemented matrix; inspect a fresh surface and test clasts separately. Common worldwide in ancient river and basin deposits.