sedimentary
Conglomerate
Conglomerate (Detrital Sedimentary Rock)
Hardness: variable (depends on clast type, usually 6-7 if quartz-rich); Color: multicolored with a tan or grey matrix; Luster: dull to earthy; Structure: clastic texture with rounded fragments (>2mm); Specific Gravity: 2.6-2.8.
- Hardness
- variable (depends on clast type, usually 6-7 if quartz-rich)
- Color
- multicolored with a tan or grey matrix
- Luster
- dull to earthy
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Physical properties
Hardness: variable (depends on clast type, usually 6-7 if quartz-rich); Color: multicolored with a tan or grey matrix; Luster: dull to earthy; Structure: clastic texture with rounded fragments (>2mm); Specific Gravity: 2.6-2.8.
Formation & geological history
Formed through the lithification of rounded gravel and boulders. Typically created in high-energy environments like fast-flowing rivers, alluvial fans, or glaciated areas where water rounds the stone fragments over time.
Uses & applications
Used primarily in the construction industry as a coarse aggregate for concrete and road sub-base. Some attractive specimens are cut and polished for ornamental use or individual 'pudding stone' collectibles.
Geological facts
Conglomerates are often referred to as 'pudding stones' because the rounded pebbles look like raisins or nuts in a pudding. They are key indicators for geologists of ancient riverbeds or shoreline environments.
Field identification & locations
Identify in the field by looking for 'stones within a stone' where the individual pebbles are noticeably rounded rather than sharp/angular. Found globally in sedimentary basins and mountain foothills.
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