sedimentary

Conglomerate

Clastic Sedimentary Rock (Conglomerate)

Hardness: Variable based on clasts (usually 6-7 if silica-rich); Color: Multi-colored clasts in a tan, gray, or brown matrix; Luster: Dull or earthy; Structure: Coarse-grained clastic texture with rounded clasts (>2mm) embedded in a finer matrix.

Hardness: Variable based on clasts (usually 6-7 if silica-rich)
Color: Multi-colored clasts in a tan, gray, or brown matrix
Luster: Dull or earthy

Identified June 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the lithification of rounded gravel and pebbles. These sediments are typically deposited in high-energy environments like fast-flowing rivers or beaches where tumbling rounds the edges of the stones.

Uses & applications

Used primarily in the construction industry as coarse aggregate for concrete and road building. Occasionally used as a decorative stone in architecture.

Geological facts

Conglomerate is often called 'puddingstone' because the rounded stones look like raisins or nuts in a pudding. It is the rounded-clast equivalent of 'breccia,' which contains angular fragments.

Field identification & locations

Identify by the presence of large, rounded pebbles cemented together. Commonly found in ancient riverbeds, alluvial fans, and glacial deposits across the globe.

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