sedimentary

Conglomerate (Asphaltic/Anthropogenic)

Clastic sedimentary rock / Bituminous mixture

AI-generated identification · may be incorrect

Hardness: 3-6 (variable based on aggregate); Color: Dark grey to black with lighter grey stone inclusions; Luster: Dull to sub-metallic; Crystal structure: Amorphous matrix with crystalline clasts; Cleavage: None (irregular fracture); Specific Gravity: 2.1-2.4.

Hardness: 3-6 (variable based on aggregate)
Color: Dark grey to black with lighter grey stone inclusions
Luster: Dull to sub-metallic

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the lithification of rounded clasts (pebbles/gravel) cemented by a fine-grained matrix. Specimens like this one, found in disturbed soil, often represent anthropogenic 'puddingstone' or historical asphalt where bitumen binds natural stone. Geological ages for natural conglomerate vary from Precambrian to Holocene.

Uses & applications

Primarily used in construction as aggregate for roads, concrete, and building stone. Fine specimens of natural conglomerate (like Jasper Conglomerate) are used in jewelry and lapidary arts.

Geological facts

Natural conglomerates are often called 'puddingstones' because the stones look like raisins in a pudding. They are key indicators of high-energy past environments like fast-moving rivers or wave-swept beaches.

Field identification & locations

Identify by looking for rounded rock fragments larger than 2mm embedded in a finer matrix. Unlike breccia, the pieces are rounded rather than angular. Commonly found in old riverbeds, glacial till, and construction sites.