sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
Hardness: variable (3-7 Mohs); Color: grey matrix with brown, tan, and orange clasts; Luster: earthy to dull; Structure: clastic texture with rounded rock fragments embedded in a fine-grained matrix; Cleavage: none; SG: 2.5-2.8
- Hardness
- variable (3-7 Mohs)
- Color
- grey matrix with brown, tan, and orange clasts
- Luster
- earthy to dull
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Physical properties
Hardness: variable (3-7 Mohs); Color: grey matrix with brown, tan, and orange clasts; Luster: earthy to dull; Structure: clastic texture with rounded rock fragments embedded in a fine-grained matrix; Cleavage: none; SG: 2.5-2.8
Formation & geological history
Formed in high-energy environments like riverbeds, alluvial fans, or beaches where water currents are strong enough to transport large rounded pebbles. These sediment layers are buried and lithified over millions of years.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete and road building. Occasionally used as ornamental stone if the clasts are colorful and well-cemented.
Geological facts
Conglomerates are often referred to as 'puddingstone' in some regions due to their resemblance to a fruit pudding. They are key indicators for geologists to locate ancient river channels.
Field identification & locations
Identify in the field by looking for rounded pebbles or cobbles (clasts) that are cemented within a finer-grained matrix. They are commonly found in regions with sedimentary basin history.
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