sedimentary
Conglomerate
Conglomerate (SiO2 matrix with various inclusions)
Hardness: variable (matrix 3-4, clasts 7); Color: brownish-tan, grey, white; Luster: earthy to dull; Structure: clastic texture with rounded to sub-angular pebbles; Cleavage: none.
- Hardness
- variable (matrix 3-4, clasts 7)
- Color
- brownish-tan, grey, white
- Luster
- earthy to dull
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Physical properties
Hardness: variable (matrix 3-4, clasts 7); Color: brownish-tan, grey, white; Luster: earthy to dull; Structure: clastic texture with rounded to sub-angular pebbles; Cleavage: none.
Formation & geological history
Formed in high-energy environments like riverbeds or alluvial fans where water rounds heavy sediment over thousands of years before burial and lithification.
Uses & applications
Used primarily in the construction industry as coarse aggregate for concrete and road fill; historically used for millstones.
Geological facts
Conglomerates are often referred to as 'puddingstone' because they resemble a fruit pudding. They are key indicators for geologists to locate ancient river systems.
Field identification & locations
Identify in the field by looking for rounded pebbles (clasts) larger than 2mm cemented in a finer-grained matrix. Found globally in ancient sedimentary basins.
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