sedimentary
Conglomerate
Clastic sedimentary rock (Psephite)
Hardness: variable (6-7 for matrix depending on silica); Color: grey matrix with pink and dark grey inclusions; Luster: dull to earthy; Texture: coarse-grained clastic with rounded clasts; Cleavage: none.
- Hardness
- variable (6-7 for matrix depending on silica)
- Color
- grey matrix with pink and dark grey inclusions
- Luster
- dull to earthy
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Physical properties
Hardness: variable (6-7 for matrix depending on silica); Color: grey matrix with pink and dark grey inclusions; Luster: dull to earthy; Texture: coarse-grained clastic with rounded clasts; Cleavage: none.
Formation & geological history
Formed by the lithification of rounded gravel and pebbles, typically in high-energy environments like riverbeds or alluvial fans. This specimen likely dates from the Phanerozoic eon.
Uses & applications
Used primarily as coarse aggregate in the construction industry for concrete and road fill; sometimes used as decorative stone in landscaping.
Geological facts
Conglomerates are essentially 'nature's concrete.' The rounding of the stones inside indicates they were transported a significant distance by water before being buried and cemented.
Field identification & locations
Identify by looking for rounded pebbles (clasts) larger than 2mm embedded in a finer-grained matrix. Commonly found in old river basins, shorelines, and glacier outwash plains.
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