sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: variable depending on clasts (typically 3-7); Color: brownish-gray with multi-colored inclusions; Luster: dull/earthy; Structure: massive with rounded clasts; Cleavage: none.
- Hardness
- variable depending on clasts (typically 3-7)
- Color
- brownish-gray with multi-colored inclusions
- Luster
- dull/earthy
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Physical properties
Hardness: variable depending on clasts (typically 3-7); Color: brownish-gray with multi-colored inclusions; Luster: dull/earthy; Structure: massive with rounded clasts; Cleavage: none.
Formation & geological history
Formed by the lithification of rounded gravel, pebbles, and sand typically in high-energy environments like riverbeds or alluvial fans. Geological age varies by site but can range from Precambrian to Recent.
Uses & applications
Primarily used as a low-grade construction aggregate, fill material, and occasionally as a decorative stone for landscaping or architectural facing.
Geological facts
Conglomerates are 'history books' of the Earth; the rounded pebbles tell a story of long-distance transport by water. Mars has conglomerate outcrops, proving the past existence of liquid rivers on the planet.
Field identification & locations
Identify in the field by looking for rounded, water-worn pebbles larger than 2mm cemented in a finer-grained matrix. Look for them in ancient river valleys or beach deposits.
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