sedimentary

Conglomerate (or Breccia)

Clastic Sedimentary Rock (Conglomeratic)

AI-generated identification · may be incorrect

Hardness: Variable based on matrix and clasts (typically 3-7 Mohs); Color: Tan/brown matrix with dark grey angular clasts; Luster: Dull or earthy; Structure: Clastic, poorly sorted; Specific Gravity: 2.3–2.6.

Hardness: Variable based on matrix and clasts (typically 3-7 Mohs)
Color: Tan/brown matrix with dark grey angular clasts
Luster: Dull or earthy

Identified March 27, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the lithification of coarse-grained sediments. In this specimen, the angularity of the dark clasts suggests it is closer to a Breccia, indicating the sediments didn't travel far from their source before being cemented by fine-grained minerals.

Uses & applications

Used primarily in the construction industry as fill material, road base, or decorative stone in landscaping. Occasionally used as a building stone if the cementing matrix is strong.

Geological facts

Sedimentary rocks like these are 'time capsules' because the individual clasts (the dark rocks inside) are actually older than the conglomerate rock itself. Most found on the surface today formed within the last 500 million years.

Field identification & locations

Identify in the field by looking for 'concrete-like' appearance where large pebbles or rock fragments are stuck together by a finer paste. Found in riverbeds, glacial deposits, and alluvial fans.