sedimentary

Conglomerate

Conglomerate (Clastic Sedimentary Rock)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (variable based on clast composition); Color: Gray to olive-green matrix with dark rounded clasts; Luster: Dull/Earthy; Structure: Clastic, containing rounded pebbles over 2mm; Cleavage: None

Hardness: 6
Color: Gray to olive-green matrix with dark rounded clasts
Luster: Dull/Earthy

Identified March 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in high-energy environments like riverbeds or alluvial fans where water current is strong enough to transport large pebbles. The rounding occurs through abrasion over thousands of years before being cemented by minerals like silica or calcite.

Uses & applications

Used primarily as coarse aggregate in construction, road base, and occasionally as decorative stone or landscaping material if the clasts are colorful.

Geological facts

Conglomerate is often called 'puddingstone' because the dark clasts in a lighter matrix resemble raisins in a pudding. It differs from Breccia, which contains sharp, angular fragments.

Field identification & locations

Identify by looking for rounded pebbles (clasts) that are visibly cemented into a finer-grained matrix. It is commonly found in ancient river systems or glacial till. Collectors look for 'Gowganda' or high-contrast varieties.