To most people the word sand means the stuff that beaches and deserts are covered with and to many of us that means sand-sized grains of the mineral quartz, the most resistant mineral at the Earth’s surface.
Quartz is insoluble and slow to weather, and so it is the stuff of many deserts and beaches. However, in a desert where the little water that falls every year creates temporary lakes, as those lakes evaporate, the minerals dissolved in the water precipitate, forming crystals of evaporite minerals like salt and gypsum.
As the winds whip across these dried up lakebeds, the crystals are swept up and piled into great glistening dunes of white gypsum sand. This is White Sands National Monument in New Mexico.
Photo from here.
More info on the park here.
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