These sparkling gypsum crystals (called selenite) are the source of sand that forms the dunes of White Sands National Monument.
My parents and I planned our trip so we would visit during one of the times the reservation-only Lake Lucero Tours are offered. You can only go here on a tour.
|Those mountains provided the source of the gypsum.|
|The white sands in a wind-swept dune after the particles have been broken up.|
But crystal formation is also an ongoing process that has been going on for thousands of years. Water that flows down into the playa is still saturated with more gypsum and more crystals form beneath the ground or during monsoon season. Though the crystals that form today tend to be smaller than the ancient crystals.
It didn’t feel right to me that we could freely walk across the crystals and feel them crunching beneath our feet. But the ranger assured us that it’s OK because they just erode away very quickly anyway and they are constantly being exposed due to erosion. Still, we were told not to collect any crystals.
What surprised me the most was that the crystals are made out of the same material as crystals in Mammoth Cave National Park in Kentucky (which is where I spent last summer). Both are gypsum, which is also what makes up drywall. They differ in shape and the crystals are called different things (selenite at White Sands, gypsum flowers at Mammoth Cave) so I think there must be something else different about them (any geologists out there?).
|Gypsum flowers in Mammoth Cave (photo from last summer)|
|Gypsum (selenite) at White Sands. It is amber in color due to organic matter, but turns white as it weathers.|
But in New Mexico, with the now arid climate, gypsum exists on the surface because it pools in the basin and also there is limited rain so we get to see the crystals on the surface before they get eroded into sand or dissolved. How cool that the conditions are “just right” for this to happen.
|So much sparkle|
Get tickets by phone or on recreation.gov one month in advance. Apparently the April or November tours have better chances that there will be water in the lake so tend to have more birds, butterflies, and flowers than we saw in December.
|Don't forget to stop by the visitor center to do their Junior Ranger program.|