sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: 3-7 (variable based on clasts/cement); Color: Grey, brown, tan matrix; Luster: Dull/Earthy; Crystal Structure: Amorphous/Clastic; Cleavage: None; Specific Gravity: 2.5-2.8
- Hardness
- 3-7 (variable based on clasts/cement)
- Color
- Grey, brown, tan matrix
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3-7 (variable based on clasts/cement); Color: Grey, brown, tan matrix; Luster: Dull/Earthy; Crystal Structure: Amorphous/Clastic; Cleavage: None; Specific Gravity: 2.5-2.8
Formation & geological history
Formed through the lithification of rounded gravel and boulders, typically in high-energy environments like riverbeds, alluvial fans, or beaches where water can round the edges of rock fragments.
Uses & applications
Used in the construction industry as coarse aggregate for concrete and road material. Attractive specimens are used as decorative stones or for teaching geological concepts.
Geological facts
Conglomerates are like a geological 'time capsule,' often containing fragments of rocks that existed millions of years before the conglomerate itself was formed.
Field identification & locations
Identify by looking for rounded rock fragments (clasts) cemented within a finer-grained matrix. Often found in ancient river systems or glacial deposits.
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