sedimentary
Conglomerate
Conglomerate rock (detrital sedimentary)
Hardness: variable (5.5-7 for quartz pebbles); Color: yellowish-green matrix with grey, white, and translucent quartz clasts; Luster: dull to vitreous; Texture: clastic, coarse-grained with rounded pebbles cementation
- Hardness
- variable (5
- Luster
- dull to vitreous
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Physical properties
Hardness: variable (5.5-7 for quartz pebbles); Color: yellowish-green matrix with grey, white, and translucent quartz clasts; Luster: dull to vitreous; Texture: clastic, coarse-grained with rounded pebbles cementation
Formation & geological history
Formed by the accumulation and lithification of rounded pebbles and gravel, typically in riverbeds, alluvial fans, or high-energy beach environments where water action rounds the rock fragments over time.
Uses & applications
Used primarily as coarse aggregate in construction, road base, decorative landscaping stones, and as geological teaching specimens.
Geological facts
Conglomerates are natural concrete-like rocks where nature cements rounded pebbles together over millions of years. The rounded shape of the internal pebbles indicates significant transportation by moving water before deposition.
Field identification & locations
Identified by visible, rounded clasts (>2mm) embedded within a fine-grained matrix. Frequently found in ancient river channels, mountain fronts, and coastal pebble beaches worldwide.
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