sedimentary

Conglomerate

Conglomerate (clastic sedimentary rock)

AI-generated identification · may be incorrect

Hardness varies by cement (usually 6-7 if silica-based); multi-colored including tans, grays, and whites; dull to earthy luster; contains rounded clasts (pebbles) larger than 2mm embedded in a finer matrix.

Identified June 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in high-energy environments like riverbeds, alluvial fans, or beaches where water movement is strong enough to round large particles before they are buried and lithified by mineral cement over millions of years.

Uses & applications

Primarily used as a coarse aggregate in the construction industry for concrete and roadbeds; sometimes used as a decorative building stone or for landscaping.

Geological facts

Conglomerate is often called 'puddingstone' in some regions due to the appearance of round 'plums' in a 'batter' of matrix. It has been discovered on Mars, providing evidence of ancient flowing water on the planet.

Field identification & locations

Identify by looking for rounded pebbles (clasts) that are cemented together; unlike Breccia, which has sharp-edged fragments. Commonly found in sedimentary basins and ancient river drainage systems worldwide.