sedimentary
Conglomerate
Conglomerate (Clastic sedimentary rock)
Hardness: variable based on clasts (usually 6-7 if quartz-rich); Color: grey matrix with tan, brown, and white clasts; Luster: dull/earthy; Texture: coarse-grained clastic; Cleavage: none; Specific Gravity: 2.6-2.8
- Hardness
- variable based on clasts (usually 6-7 if quartz-rich)
- Color
- grey matrix with tan, brown, and white clasts
- Luster
- dull/earthy
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Physical properties
Hardness: variable based on clasts (usually 6-7 if quartz-rich); Color: grey matrix with tan, brown, and white clasts; Luster: dull/earthy; Texture: coarse-grained clastic; Cleavage: none; Specific Gravity: 2.6-2.8
Formation & geological history
Formed through the lithification of rounded gravel and boulders typically deposited in high-energy environments like riverbeds, alluvial fans, or glacial meltwater streams.
Uses & applications
Primarily used in the construction industry as coarse aggregate for concrete and road base; occasionally used as decorative stone in landscaping.
Geological facts
Conglomerate is often called 'puddingstone' because the rounded clasts resemble raisins or nuts in a pudding. It indicates that the sediment was transported a significant distance to round the edges of the stones.
Field identification & locations
Identify by looking for rounded rock fragments (larger than 2mm) cemented in a finer-grained matrix. Commonly found in ancient river channels and mountain fronts.
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