sedimentary
Conglomerate
Conglomerate (Clastic sedimentary rock)
Clastic texture with rounded clasts (>2mm); Mohs hardness varies (6-7 for quartz clasts); colors range from tan to brown; dull to earthy luster; poorly sorted matrix.
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Physical properties
Clastic texture with rounded clasts (>2mm); Mohs hardness varies (6-7 for quartz clasts); colors range from tan to brown; dull to earthy luster; poorly sorted matrix.
Formation & geological history
Formed in high-energy environments like riverbeds or alluvial fans over millions of years (often Paleozoic or Mesozoic age) where large pebbles are rounded by water and cemented by silt, clay, or chemicals.
Uses & applications
Primarily used as a low-value construction aggregate, railroad ballast, or occasionally as ornamental stone if it contains attractive semi-precious pebbles.
Geological facts
Often called 'puddingstone' in some regions; it is essentially a lithified gravel bed. The rounded shape of the pebbles indicates they traveled a long distance from their source.
Field identification & locations
Identify by the presence of large, rounded pebbles naturally cemented together. Common near ancient or active river systems and mountain fronts across the globe.
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