sedimentary

Conglomerate

Sedimentary Conglomerate

Hardness typically varies from 6 to 7 depending on the constituent pebbles (often quartz). Color is typically brown, tan, or multicolored. Luster is dull to earthy. Composed of rounded to sub-rounded gravel-sized clasts set in a finer-grained matrix of sand, silt, or clay.

Identified August 3, 2026More sedimentary →

Explore Conglomerate in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed by the consolidation and cementation of gravel and rounded fragments of rock, transported by high-energy water currents in rivers, streams, or coastal environments, and deposited over millions of years.

Uses & applications

Used primarily in the construction industry as crushed stone for road base, concrete aggregate, and sometimes as an architectural or decorative building stone.

Geological facts

Conglomerates are often referred to colloquially as 'puddingstone' because their appearance resembles a plum pudding containing pieces of fruit embedded in a batter. The degree of rounding of the clasts indicates the distance the material was transported by water.

Field identification & locations

Easily identified by its distinctive 'gravel embedded in concrete' appearance. It is found worldwide in sedimentary basins, river beds, and ancient alluvial fans.