Without sand, engineering would be stuck in the Middle Ages. Wooden houses would line mud-packed streets, and Silicon Valley would be, well, just a valley. Sand is the building material of modern cities, and we use more of this resource than any other except water and air. Now we’re running out of it.
Hear why the Roman recipe for making concrete was lost until the 19th century, and about the super-secret mine in North Carolina that makes your smartphone possible.