sedimentary

Conglomerate

Clastic sedimentary rock (composed mostly of SiO2)

Hardness: 6.5-7 (variable based on clasts); Color: Tan/brown matrix with dark clasts; Luster: Dull to earthy; Crystal structure: Amorphous/microcrystalline matrix; Cleavage: None; Specific gravity: 2.6-2.8.

Hardness: 6
Color: Tan/brown matrix with dark clasts
Luster: Dull to earthy

Identified July 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the lithification of rounded gravel and pebbles in high-energy environments like riverbeds or beaches. This specimen appears to be a small, water-worn pebble smoothed by fluvial or coastal erosion.

Uses & applications

Commonly used as aggregate in the construction industry (concrete) or for decorative landscaping. Small rounded specimens like this are predominantly of interest to amateur collectors.

Geological facts

Conglomerates are known as nature's 'junk drawer' because they can contain a wide variety of older rock fragments. The rounded shape of the internal pebbles indicates they traveled a long distance in water before being buried.

Field identification & locations

Identify by looking for distinct, rounded clasts (pebbles) cemented within a finer-grained matrix. Found globally in ancient river basins and coastal deposits.

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