sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: 6-7 (approximate based on clast content); Color: Gray, tan, white with multicolored rounded clasts; Luster: Dull/Earthy; Structure: Clastic with rounded grains/pebbles; Cleavage: None
- Hardness
- 6-7 (approximate based on clast content)
- Color
- Gray, tan, white with multicolored rounded clasts
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (approximate based on clast content); Color: Gray, tan, white with multicolored rounded clasts; Luster: Dull/Earthy; Structure: Clastic with rounded grains/pebbles; Cleavage: None
Formation & geological history
Formed by the lithification of rounded pebbles and gravel-sized particles, typically in high-energy environments like riverbeds or coastal beaches. The rounding suggests long-distance transport by water.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete, as road ballast, and occasionally as ornamental building stone if particularly colorful.
Geological facts
Conglomerate is often called "puddingstone" because the rounded clasts trapped in the matrix resemble raisins or fruit in a pudding. It can vary significantly in age from Precambrian to Cenozoic.
Field identification & locations
Identify in the field by the presence of rounded (not angular) pebbles cemented together in a finer-grained matrix. Found in ancient stream beds, alluvial fans, and glacial deposits.
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