sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: Variable based on clasts (often 6-7 if quartz), Color: Mixed reddish-brown, tan, and gray, Luster: Dull to earthy (matrix) with vitreous clasts, Structure: Clastic with rounded grains larger than 2mm
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Physical properties
Hardness: Variable based on clasts (often 6-7 if quartz), Color: Mixed reddish-brown, tan, and gray, Luster: Dull to earthy (matrix) with vitreous clasts, Structure: Clastic with rounded grains larger than 2mm
Formation & geological history
Formed in high-energy environments like riverbeds or alluvial fans where rounded pebbles are deposited and later cemented by minerals like silica or calcite. Age ranges from millions to billions of years depending on location.
Uses & applications
Used as aggregate in construction, road base material, and occasionally as decorative stone for landscaping or building facades.
Geological facts
Conglomerate is often nicknamed 'puddingstone' because its rounded clasts resemble fruit in a pudding. It is an indicator of ancient river systems or active tectonic environments.
Field identification & locations
Identify in the field by looking for naturally rounded pebbles cemented into a finer-grained matrix. Found globally in ancient basins, near mountain ranges, and along coastlines.
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