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Cities Made of Sand

Cities Made of Sand

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 Sand. It circles the continents and stretches across deserts. There’s so much, you’d think we’d never run out. But in many places, we are. The term “sand” just refers to the size of the grain. It can be made of many materials, but the sand we value most is made of quartz. We use it to make glass, computer chips, roof shingles, paints, sealants, cosmetics, and much more. But we use it most in concrete, which is about two-thirds sand. There are hundreds of tons in the average American house—and billions of tons in cities. And therein lies the rub. Because sand is so heavy, it’s expensive to transport, meaning most sand used in buildings is local. And the rapid growth of new cities, particularly in China, India, and other developing countries, has used up much of the high-quality local supply. Beach sand is not a good choice for concrete—the salt can corrode the reinforcing steel. Yet some coastal cities and island nations have stripped their beaches bare for the building trade, leaving only rock. Other communities, like Dubai and Phoenix, use their local desert sand, which is often poor quality, as well. It’s high in clay, chalk, and iron oxide. Shortage of good-quality sand has led China to begin importing it. Elsewhere, like in India, a black market has sprung up, complete with sand mafias! In the future, we’re likely to see a growing global trade in this surprisingly precious commodity.
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