How gravel and crushed stone are made

Almost half of all gravel production goes into concrete as aggregate.

stations: 3
things downstream: 5

The short version

Gravel is loose rock between 2 and 64 millimeters or so, laid down by rivers and glaciers. It is dug from pits and river flood plains. Crushed stone is made instead by blasting solid rock and breaking it in crushers. Both are screened by size and used in concrete and under roads.

Dig the river deposit

Natural gravel sits in stream channels, river flood plains and glacial deposits. Excavators and dredges lift it out together with its sand and clay.
Crush solid rock

Where natural gravel is scarce, quarries blast granite, limestone or dolomite and feed it into crushers. The pieces are angular, and they lock together under a road.
Screen by size

Screens sort the material into grades, from fine to coarse. Crushed and graded stone may be blended with fines for surfacing roads and driveways.

End of the lineGravel and crushed stone Next it goes into asphalt, concrete, asphalt road and 1 more.

Worth repeating

Quartz is the most common mineral in gravel, because it is hard, chemically inert and lacks cleavage planes.
In 2020, sand and gravel together made up 23% of all industrial mineral production in the United States.