sedimentary

Conglomerate

Clastic Sedimentary Rock

Hardness: variable (3-7 depending on cement and clasts); Color: dark matrix with multicolored rounded pebbles; Luster: dull to earthy matrix; Structure: clastic texture with large rounded fragments; Cleavage: none.

Hardness: variable (3-7 depending on cement and clasts)
Color: dark matrix with multicolored rounded pebbles
Luster: dull to earthy matrix

Identified June 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the lithification of rounded gravel and pebbles in high-energy environments like riverbeds, beaches, or alluvial fans. The rounding indicates significant transport distance from the source.

Uses & applications

Primarily used in construction as aggregate for concrete, road base, and occasionally as a decorative building stone or for geological education.

Geological facts

Conglomerate is often confused with Breccia, which contains angular fragments. It is often referred to as 'puddingstone' because it resembles fruit embedded in a darker cake matrix.

Field identification & locations

Identified in the field by large (over 2mm), rounded clasts cemented together. Found globally in ancient river systems. Collectors look for unique pebble colors or ancient fossil inclusions.