sedimentary

Conglomerate

Conglomerative Sedimentary Rock

Hardness varies by clast type (usually 6-7 if quartz-rich); Color: Grey, brown, or multi-colored depending on clasts; Luster: Dull/Earthy matrix with variable clast luster; Crystal structure: Non-crystalline/Clastic; Specific Gravity: 2.6-2.9.

Color: Grey, brown, or multi-colored depending on clasts
Luster: Dull/Earthy matrix with variable clast luster

Identified March 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the lithification of rounded gravel and boulders (clasts) larger than 2mm, usually in high-energy environments like fast-flowing rivers, alluvial fans, or glacial meltwater deposits.

Uses & applications

Primarily used as a coarse aggregate in the construction industry for concrete and road beds. Some aesthetically pleasing varieties (Puddingstone) are used for ornamental carvings or as decorative garden stones.

Geological facts

Also known as 'Puddingstone' because the rounded rocks in the matrix resemble raisins in a pudding. It is often used by geologists to determine the direction and energy of ancient river flows.

Field identification & locations

Identify in the field by looking for 'rounded' pebbles or rocks cemented naturally within a finer-grained matrix (sand or silt). Commonly found in ancient riverbeds or mountain bases globally. Collectors look for unique colors or fossil inclusions.