sedimentary

Conglomerate (likely polymictic)

Polymictic conglomerate; a coarse clastic sedimentary rock containing lithic and mineral clasts

AI-generated identification · may be incorrect

Visible, poorly sorted pebble- to gravel-sized fragments of varied colors and compositions in a finer matrix; clasts appear mostly angular to subrounded. Hardness and luster vary by constituent; the image does not show enough detail to determine cement or specific gravity.

Identified October 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when gravel and rock fragments are deposited in high-energy settings such as river channels, alluvial fans, or beaches, then compacted and cemented. Its age cannot be determined from the image.

Uses & applications

Usually used locally as aggregate or decorative building stone; distinctive specimens may be collected or used as ornamental slabs.

Geological facts

Conglomerates contain rounded clasts, while rocks dominated by angular fragments are technically breccias; this specimen may include both shapes.

Field identification & locations

Look for conspicuous gravel-sized fragments cemented into one rock, with a mix of clast types. Common worldwide in ancient river and fan deposits; estimated value is about $5–$30 for a small, ordinary specimen, more if polished or unusually attractive.