sedimentary

Conglomerate

Clastic Sedimentary Rock

Hardness varies depending on clasts and cement (typically Mohs 6-7 if quartz-rich); multicolored due to varied mineral and rock fragments; dull luster; clastic texture with rounded gravel-sized fragments (pebbles, cobbles, boulders) set in a finer-grained matrix of sand, silt, or clay; no distinct cleavage.

Identified August 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the consolidation and cementation of rounded, water-worn gravel and pebble-sized rock fragments, typically deposited in high-energy environments such as fast-flowing rivers, alluvial fans, or beach zones over millions of years.

Uses & applications

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

Geological facts

Conglomerates are often referred to as 'nature's concrete' because they naturally consist of gravel and boulders cemented together by minerals like silica, calcite, or iron oxide.

Field identification & locations

Easily identified in the field by its distinct 'plum-pudding' appearance, featuring rounded pebbles visibly embedded within a finer matrix. Found worldwide in ancient riverbeds and sedimentary basins.