Djibouti

Not everything that looks like sand is ordinary sand. But by size alone, salt can be sand.

At Lake Assal in Djibouti, white granular fields stretch along the water. The grains are salt, not the quartz or other materials we usually think of as sand.

Geologically, sand is defined mainly by grain size: 0.063–2 millimetres. A salt grain within that range therefore counts as a grain of sand, even though the material itself is halite, or rock salt.

Lake Assal lies around 153 metres below sea level, the lowest point in Africa, and salt has been extracted and transported from here for generations.

Sand is not a particular material. It is a size.