sedimentary
Conglomerate
Conglomerate (SiO2, Al2O3, Fe2O3, CaCo3)
Hardness (Mohs): 6.5-7 (variable based on matrix); Color: Brown, tan, reddish with inclusions of grey and white; Luster: Dull to earthy; Crystal structure: Non-crystalline matrix with various clast structures; Cleavage: None
- Color
- Brown, tan, reddish with inclusions of grey and white
- Luster
- Dull to earthy
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Physical properties
Hardness (Mohs): 6.5-7 (variable based on matrix); Color: Brown, tan, reddish with inclusions of grey and white; Luster: Dull to earthy; Crystal structure: Non-crystalline matrix with various clast structures; Cleavage: None
Formation & geological history
Formed through the lithification of rounded gravel and boulders typically found in riverbeds or coastal environments. Often millions of years old, dating from various geological periods where high-energy water flow occurred.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete, as fill material, or as a decorative stone in landscaping and architecture.
Geological facts
Conglomerate is often called "puddingstone" because the rounded clasts resemble raisins or nuts in a pudding. It indicates a history of high-energy environment like a fast-moving river or a beach with strong waves.
Field identification & locations
Identify by the presence of large, rounded rock fragments (clasts) greater than 2mm in diameter cemented within a finer-grained matrix. Found in sedimentary basins worldwide.
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