sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: 3-7 (variable based on matrix and clasts); Color: Variable greys, tans, and browns; Luster: Dull to earthy; Texture: Coarse-grained with rounded clasts; Cleavage: None
- Hardness
- 3-7 (variable based on matrix and clasts)
- Color
- Variable greys, tans, and browns
- Luster
- Dull to earthy
Identified More sedimentary →
Explore Conglomerate in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-7 (variable based on matrix and clasts); Color: Variable greys, tans, and browns; Luster: Dull to earthy; Texture: Coarse-grained with rounded clasts; Cleavage: None
Formation & geological history
Formed in high-energy environments like riverbeds, beaches, or alluvial fans where water currents are strong enough to transport large pebbles. Over millions of years, these sediments are buried and cemented together by minerals like calcite or quartz.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete and as fill material. Occasionally used as a decorative stone in landscaping or interior design (puddingstone gems).
Geological facts
Conglomerate rocks are often called 'puddingstones' because the rounded pebbles look like raisins or plums inside a pudding. They are key indicators for geologists to locate ancient river systems.
Field identification & locations
Identify in the field by looking for rounded, smooth pebbles or cobbles embedded within a finer-grained sandy or silty matrix. Common in mountainous regions and coastal areas.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary