Conglomerate

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.

Identified on: 5/14/2026

Mode: Standard