2023, Saudi Arabia paid approximately $140,000 to import construction-grade sand from Australia. The figure is small in dollar terms, but the trade flow it represents is the visible part of a much larger phenomenon. Saudi Arabia, a country dominated by some of the largest sand deserts on Earth, cannot use the sand in its own deserts for most construction work. The grains are the wrong shape. They have been polished smooth by thousands of years of wind erosion, and smooth round grains do not bond with cement in the way that concrete requires. Construction-grade sand has to come from somewhere else — from rivers, lakes, seabeds, or quarries, where the grains have been broken sharp by water rather than rounded by air. For a country building cities the size of NEOM and the Red Sea Project, the result is that even abundant sand is the wrong sand, and imports become a structural feature of the economy.