sedimentary

Conglomerate

Conglomerate (clastic sedimentary rock)

AI-generated identification · may be incorrect

Hardness: variable (depends on clast composition); Color: mottled, multi-colored; Luster: earthy/dull; Structure: rounded clasts (>2mm) in a fine-grained matrix; Cleavage: none.

Hardness: variable (depends on clast composition)
Color: mottled, multi-colored
Luster: earthy/dull

Identified April 8, 2026More sedimentary →

Explore Conglomerate in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: variable (depends on clast composition); Color: mottled, multi-colored; Luster: earthy/dull; Structure: rounded clasts (>2mm) in a fine-grained matrix; Cleavage: none.

Formation & geological history

Formed through the lithification of rounded gravel and boulders. These are typically deposited in high-energy environments like fast-flowing rivers, alluvial fans, or glacial wash where water rounds the stones over time.

Uses & applications

Used primarily in the construction industry as coarse aggregate for concrete and road fill. Occasionally used as ornamental stone if the clasts are colorful or unique.

Geological facts

Conglomerates are often called 'puddingstone' because they resemble a fruit pudding. Curiosity Rover discovered conglomerate rocks on Mars, providing evidence of ancient flowing water on the planet.

Field identification & locations

Identify in the field by looking for large, rounded pebbles or cobbles cemented together. Commonly found in ancient riverbeds or mountain bases. Collectors look for 'healed' fractures where the stone has broken through the pebbles.