Ready for a (slightly dirty) adventure and some geological wonders in Oklahoma? From April to October each year, you can visit the Salt Plains National Wildlife Refuge and dig for your very own selenite crystals … for free! In fact, this area is the only place in the world where you can find this unique, hourglass-shaped crystallized gypsum.
Here are 6 fun facts about selenite crystals:
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Where the Crystals Grow
The Salt Plains National Wildlife Refuge contains over 11,000 acres of salt flats and is the perfect environment for the selenite crystals to naturally form just below the salt-encrusted surface. As the salty water evaporates from the wet soil, selenite begins to grow!
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How They Get Their Unique Look
As the crystals form, the sand, clay, and iron oxide that is found in the soil become trapped inside. This process creates the crystals’ distinctive hourglass shape and unique chocolate-brown coloring. -
Digging Helps the Ecosystem
Digging for these crystals in the designated dig sites is actually helpful for the environment! Visitors are encouraged to leave their holes unfilled because the holes provide nesting and sheltering sites for migratory birds, small mammals, and even insects.
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They’re Surprisingly Soft
Selenite crystals are soft! On the Mohs hardness scale, which ranks how easily minerals can be scratched, selenite scores a 2 out of 10. For comparison, talc (like baby powder) is the softest at 1, and diamonds top the chart at 10. Because selenite is so soft, it can even be scratched with a fingernail. -
Oklahoma’s Official Crystal
The hourglass selenite crystal is the state crystal of Oklahoma! In fact, it is the only official state crystal in the entire U.S. That speaks to just how special these unique crystals are to the state. -
Take a Piece Home
Visitors are allowed to take home a generous number of found crystals … up to 10 pounds worth, to be exact!
Find More Hidden Gems in Oklahoma!
Digging for selenite crystals is just one of the amazing adventures Oklahoma offers. Want to discover more about Oklahoma’s hidden gems? Check out our Oklahoma state unit from our Hit the Road Geography curriculum! Packed with stories, activities, and adventure, this hands-on state unit is the perfect way to discover the Sooner State without ever leaving your home.
