These are perfectly cubical salt crystals, spotted at Salar de Uyuni, the world’s largest salt flat, located in Bolivia.
Each crystal belongs to a specific crystal system – for salt it’s the cubic system. This means that the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals, and this is why we see these extremely straight crystals.
Salar de Uyuni is the legacy of a prehistoric lake that went dry, leaving behind a desert-like, 11,000-sq.-km. landscape of bright-white salt, rock formations and cacti-studded islands. It is covered by a few meters of salt crust, which has an extraordinary flatness.