sedimentary

Conglomerate

Conglomerate (clastic sedimentary rock)

AI-generated identification · may be incorrect

Hardness varies by cement (usually 6-7 if siliceous); Color: grey, tan, or brown matrix with multicolored inclusions; Luster: dull to earthy matrix with vitreous clasts; Structure: coarse-grained clastic texture containing rounded clasts (pebbles) larger than 2mm.

Color: grey, tan, or brown matrix with multicolored inclusions
Luster: dull to earthy matrix with vitreous clasts

Identified May 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the lithification of rounded gravel and pebbles, typically in high-energy environments like riverbeds, alluvial fans, or glacial meltwater streams where water velocity was high enough to transport large particles.

Uses & applications

Used primarily in the construction industry as coarse aggregate for concrete and road base; occasionally used as decorative stone in landscaping or interior flooring.

Geological facts

Conglomerate is often called "puddingstone" because the rounded pebbles in the matrix look like raisins or nuts in a pudding. It serves as a geological indicator of ancient river systems or shorelines.

Field identification & locations

Identify in the field by looking for large, rounded rock fragments (clasts) cemented together in a finer-grained matrix. It is found globally in sedimentary basins. For collectors, look for unique colors or jasper/agate inclusions.