Conglomerate

Physical Properties

Hardness: Variable (6-7 for clasts, lower for matrix); Color: Tan, brown, and green with white quartz pebbles; Luster: Dull/Earthy; Structure: 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, alluvial fans, or beaches. These specimens can range from Cenozoic to Precambrian in age.

Uses & Applications

Primarily used as coarse aggregate in the construction industry for concrete and road fill. Occasionally used as a decorative stone in architecture if well-cemented.

Geological Facts

Conglomerates are often referred to as 'puddingstone' because the rounded pebbles look like raisins or nuts in a pudding. They are key indicators of past water flow direction and energy levels.

Field Identification & Locations

Identify in the field by looking for rounded, water-worn pebbles (clasts) larger than 2mm cemented together. Commonly found in ancient river systems and coastal regions.

Identified on: 4/25/2026

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