Distinctive features:  
Boulders, pebbles, or shingle, set in fine-grained matrix, sometimes resembling coarse concrete. 

Colour: 
Variable, depending on the type of rock fragments. 

Texture and granularity: 
Variable. 

Composition: 
Rounded rock fragments set in a fine-grained matrix. 

Field associations: 
Derived from beach, lake and river deposits of boulders, pebbles and gravel. Often found near deposits of sandstone and arkose. 

 

Worldwide.

 

Aggregate, ornamental when highly compacted forms are cut and polished.