Journey to the Tularosa Basin in southern New Mexico’s Chihuahuan Desert and you’ll find more of this powdery white sand. A lot more. Four and a half billion tons of it makes up the largest gypsum dune field on earth, stretching more than 200 miles. Gypsum dunes are rare, as the mineral is so fine it’s said to dissolve in rain as easily as sugar melts in ice tea. Rain dissolves the gypsum here in the Tularosa Basin, too, but because there’s no natural drainage outlet, once the rain evaporates, the gypsum is left in fine crystals.
