sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: variable based on matrix (3-7); Color: multicolored, often gray, tan, or brown; Luster: dull to earthy; Texture: coarse-grained with rounded clasts larger than 2mm.
- Hardness
- variable based on matrix (3-7)
- Color
- multicolored, often gray, tan, or brown
- Luster
- dull to earthy
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Physical properties
Hardness: variable based on matrix (3-7); Color: multicolored, often gray, tan, or brown; Luster: dull to earthy; Texture: coarse-grained with rounded clasts larger than 2mm.
Formation & geological history
Formed from the lithification of rounded water-worn fragments such as pebbles, cobbles, and gravel. Typically found in riverbeds, alluvial fans, or beach environments where high-energy water movement rounds the stones.
Uses & applications
Used primarily as low-grade construction aggregate, fill material, and occasionally as decorative dimension stone if the matrix is well-cemented.
Geological facts
Conglomerate is often nicknamed 'puddingstone' due to its resemblance to a fruit-filled dessert. These rocks are excellent indicators of ancient high-energy water environments like fast-moving rivers.
Field identification & locations
Look for rounded smooth pebbles 'cemented' together within a finer-grained matrix. It is commonly found in sedimentary basins and along ancient fault lines.
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