Except for water and air, sand is the natural resource that we consume more than any other - more than oil, more than natural gas. Every concrete building and paved road on Earth, every computer screen and silicon chip, exists because of sand. From Egypt''s pyramids to the Hubble telescope, from the world''s tallest skyscraper to the sidewalk below it, from Chartres'' stained-glass windows to Chihuly sculptures to your iPhone, sand shelters us, empowers us, engages us, and inspires us. And we''re running out of it.