sedimentary
Conglomerate
Clastic sedimentary rock (Conglomerate)
Hardness: 6.5-7 (variable based on clasts); Color: Brown, gray, tan; Luster: Dull/Earthy; Structure: Clastic, containing rounded pebbles cemented in a fine-grained matrix; Specific Gravity: 2.6-2.8
- Hardness
- 6
- Color
- Brown, gray, tan
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6.5-7 (variable based on clasts); Color: Brown, gray, tan; Luster: Dull/Earthy; Structure: Clastic, containing rounded pebbles cemented in a fine-grained matrix; Specific Gravity: 2.6-2.8
Formation & geological history
Formed in high-energy environments like riverbeds, beaches, or alluvial fans where water flow is strong enough to transport large particles. The rounded shape indicates long-distance transport. Age can range from Proterozoic to Cenozoic.
Uses & applications
Commonly used as coarse aggregate in the construction industry for concrete and road beds. More attractive specimens are used for architectural facing or as decorative garden stones.
Geological facts
Conglomerates are known as 'puddingstones' in some regions due to their appearance of fruit in pudding. They were famously discovered on Mars by the Curiosity rover, proving that liquid water once flowed there.
Field identification & locations
Identify by looking for rounded pebbles (clasts) larger than 2mm embedded in a finer matrix of sand or silt. Found globally in ancient riverbeds and mountain foothills.
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