It may be little more than grains of weathered rock, and can be found in deserts and on beaches around the world, but sand is also the world’s second most consumed natural resource.

A South African entrepreneur shot dead in September. Two Indian villagers killed in a gun battle in August. A Mexican environmental activist murdered in June.

Though separated by thousands of miles, these killings share an unlikely cause. They are some of the latest casualties in a growing wave of violence sparked by the struggle for one of the 21st Century’s most important, but least appreciated, commodities: ordinary sand.

Trivial though it may seem, sand is a critical ingredient of our lives. It is the primary raw material that modern cities are made from. The concrete used to construct shopping malls, offices, and apartment blocks, along with the asphalt we use to build roads connecting them, are largely just sand and gravel glued together. The glass in every window, windshield, and smart phone screen is made of melted-down sand. And even the silicon chips inside our phones and computers – along with virtually every other piece of electronic equipment in your home – are made from sand.