sedimentary
Conglomerate
Conglomerate (SiO2, CaCO3 dominant)
Hardness: Variable (typically 3-7 depends on matrix/clasts); Color: Grey, tan, brown; Luster: Dull to earthy; Structure: Clastic, containing rounded fragments; Cleavage: None; Specific Gravity: 2.1-2.9
- Hardness
- Variable (typically 3-7 depends on matrix/clasts)
- Color
- Grey, tan, brown
- Luster
- Dull to earthy
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Physical properties
Hardness: Variable (typically 3-7 depends on matrix/clasts); Color: Grey, tan, brown; Luster: Dull to earthy; Structure: Clastic, containing rounded fragments; Cleavage: None; Specific Gravity: 2.1-2.9
Formation & geological history
Formed in high-energy river environments or alluvial fans where water carries large sediments and rounds them before deposition. Cementation occurs over millions of years through minerals like calcite or silica.
Uses & applications
Used as a fill material in heavy construction, road building, and occasionally as structural stone or decorative concrete aggregate.
Geological facts
Conglomerate is often called "puddingstone" because the rounded rocks look like raisins in a pudding. It indicates ancient riverbeds or coastlines.
Field identification & locations
Identify by the presence of rounded pebbles (clasts) larger than 2mm embedded in a finer-grained matrix. Found globally in ancient sedimentary basins.
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