White Sands is 275 square miles of white sand dunes composed of gypsum crystals. It is the largest gypsum dune field in the world. Unlike dunes made of quartz-based sand crystals, the gypsum does not readily convert the sun’s energy into heat and thus can be walked upon safely with bare feet, even in the hottest summer months. Because the park lies completely within the White Sands Missile Range, the park is subject to closure for safety reasons when tests are conducted on the missile range. On average, tests occur about twice a week, for a duration of one to two hours. White Sands Missile Range is where the first atom bomb was detonated. [wikipedia]