It may come as a surprise that sand is one of the world’s biggest traded commodities by volume (if not value). Of the nearly 59 billion tonnes of material mined every year, 68 to 85 per cent is sand and gravel. The world consumes more than 40 billion tonnes of sand a year – used for construction, land reclamation, shoreline development, and road-building – a rate far faster than the natural replenishment of the stuff by rivers or on beaches.76 Remarkably, the abundant sand of the Arabian deserts on the Peninsula is thought inappropriate for making concrete. Concrete mixing requires angular sand, which is either marine or riparian, mined from beaches or rivers.77 Desert sand, eroded by winds, is far too rounded and smooth.78