sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness varies by cement/clasts (typically 3-7 Mohs); Color: Mixed (red, pink, grey, green); Luster: Dull to earthy; Structure: Clastic with rounded fragments over 2mm; Cleavage: None.
- Color
- Mixed (red, pink, grey, green)
- Luster
- Dull to earthy
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Physical properties
Hardness varies by cement/clasts (typically 3-7 Mohs); Color: Mixed (red, pink, grey, green); Luster: Dull to earthy; Structure: Clastic with rounded fragments over 2mm; Cleavage: None.
Formation & geological history
Formed in high-energy environments like fast-moving rivers or beaches where large pebbles are rounded by water and later cemented by minerals like silica, calcite, or iron oxide.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete and as a structural fill; occasionally used as a decorative stone in landscaping or interior design.
Geological facts
Conglomerates are known as 'puddingstones' because they resemble a fruit pudding. They provide geologists with snapshots of ancient river systems and the parent rocks that existed millions of years ago.
Field identification & locations
Identify by looking for rounded, water-worn pebbles larger than 2mm embedded in a finer-grained matrix. Found in sedimentary basins, ancient riverbeds, and mountain bases.
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