sedimentary

Conglomerate

Conglomerate (Clastic sedimentary rock)

Hardness: variable based on clasts (usually 6-7 if quartz-rich); Color: grey matrix with tan, brown, and white clasts; Luster: dull/earthy; Texture: coarse-grained clastic; Cleavage: none; Specific Gravity: 2.6-2.8

Hardness: variable based on clasts (usually 6-7 if quartz-rich)
Color: grey matrix with tan, brown, and white clasts
Luster: dull/earthy

Identified May 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the lithification of rounded gravel and boulders typically deposited in high-energy environments like riverbeds, alluvial fans, or glacial meltwater streams.

Uses & applications

Primarily used in the construction industry as coarse aggregate for concrete and road base; occasionally used as decorative stone in landscaping.

Geological facts

Conglomerate is often called 'puddingstone' because the rounded clasts resemble raisins or nuts in a pudding. It indicates that the sediment was transported a significant distance to round the edges of the stones.

Field identification & locations

Identify by looking for rounded rock fragments (larger than 2mm) cemented in a finer-grained matrix. Commonly found in ancient river channels and mountain fronts.

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