sedimentary

Conglomerate

Conglomerate (Sedimentary Rock)

Composed of rounded clasts (pebbles) of varying sizes cemented together. Hardness: 6.5-7 (for the quartz/chert clasts). Color: Multi-colored with orange, tan, and gray matrix. Luster: Dull/Earthy. Cleavage: None.

Hardness: 6
Color: Multi-colored with orange, tan, and gray matrix
Luster: Dull/Earthy

Identified July 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in high-energy environments like riverbeds or beaches where water action rounds the rock fragments before they are buried and cemented by minerals like silica or calcium carbonate.

Uses & applications

Primarily used as coarse aggregate in construction; can be used as a decorative stone in landscaping or as a lower-quality building stone.

Geological facts

Conglomerate is often called "puddingstone" because the dark matrix and round pebbles resemble a plum pudding. It is one of the easiest sedimentary rocks to identify due to its chunky, visible clasts.

Field identification & locations

Look for rounded, water-worn pebbles larger than 2mm embedded in a finer-grained matrix. Found globally in ancient river systems. Collectors look for specific 'puddingstone' types with colorful inclusions.