sedimentary

Conglomerate

Conglomerate (clastic sedimentary rock)

Hardness: 3-7 (variable based on clast composition); Color: Gray, brown, or buff; Luster: Dull/Earthy; Crystal Structure: Clastic (rounded fragments in a matrix); Cleavage: None; Specific Gravity: 2.1-2.6

Hardness: 3-7 (variable based on clast composition)
Color: Gray, brown, or buff
Luster: Dull/Earthy

Identified July 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the lithification of rounded gravel and pebbles, typically in high-energy environments like fast-moving rivers, alluvial fans, or receding shorelines. Can vary greatly in geological age.

Uses & applications

Primarily used in the construction industry as coarse aggregate for concrete, as a decorative building stone, and occasionally in landscape architecture.

Geological facts

Known as 'puddingstone' in some regions due to the appearance of raisins in a pudding. It is distinguishable from breccia because the fragments are rounded rather than angular, indicating long-distance transport.

Field identification & locations

Identify by looking for rounded pebbles (clasts) larger than 2mm cemented into a finer-grained matrix. Found globally in ancient riverbeds and mountainous debris fields.

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Clastic Sedimentary Rock Grain (SiO2 dominated)

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Sandstone

Arenite (primarily SiO2)

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