sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness varies by cement (usually 6-7 if silica-based); multi-colored including tans, grays, and whites; dull to earthy luster; contains rounded clasts (pebbles) larger than 2mm embedded in a finer matrix.
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Physical properties
Hardness varies by cement (usually 6-7 if silica-based); multi-colored including tans, grays, and whites; dull to earthy luster; contains rounded clasts (pebbles) larger than 2mm embedded in a finer matrix.
Formation & geological history
Formed in high-energy environments like riverbeds, alluvial fans, or beaches where water movement is strong enough to round large particles before they are buried and lithified by mineral cement over millions of years.
Uses & applications
Primarily used as a coarse aggregate in the construction industry for concrete and roadbeds; sometimes used as a decorative building stone or for landscaping.
Geological facts
Conglomerate is often called 'puddingstone' in some regions due to the appearance of round 'plums' in a 'batter' of matrix. It has been discovered on Mars, providing evidence of ancient flowing water on the planet.
Field identification & locations
Identify by looking for rounded pebbles (clasts) that are cemented together; unlike Breccia, which has sharp-edged fragments. Commonly found in sedimentary basins and ancient river drainage systems worldwide.
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