sedimentary

Conglomerate

Sedimentary Conglomerate with Basaltic Clast

AI-generated identification · may be incorrect

Hardness: 3-7 (variable based on matrix and clasts); Color: Grey, tan, brown; Luster: Dull or earthy; Structure: Clastic; Cleavage: None; SG: 2.5-2.8

Hardness: 3-7 (variable based on matrix and clasts)
Color: Grey, tan, brown
Luster: Dull or earthy

Identified June 27, 2026More sedimentary →

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Physical properties

Hardness: 3-7 (variable based on matrix and clasts); Color: Grey, tan, brown; Luster: Dull or earthy; Structure: Clastic; Cleavage: None; SG: 2.5-2.8

Formation & geological history

Formed when large rounded fragments (clasts) are cemented together by finer-grained matrix like sand or silt. This specimen shows a large basaltic cobble partially encased in a lithified sandy matrix, likely formed in a high-energy river or beach environment.

Uses & applications

Primarily used as coarse aggregate in construction, road base, or as an ornamental stone in landscaping. Some unique specimens serve as decorative curiosities for collectors.

Geological facts

Conglomerates are often called puddingstones because of their resemblance to Christmas pudding. They provide geologists with a record of ancient water flow direction and energy levels.

Field identification & locations

Identify by looking for rounded rock fragments of various sizes bonded together by a natural mineral cement. Large rounded stones sticking out of a finer 'concrete-like' body are characteristic. Found in riverbeds and coastal areas.