[Rockhounds] Odd white structures have been appearing at Utah's Great Salt Lake the past few winters, alarming park rangers.

[Kreigh Tomaszewski]

Angelic Anderson crouched down and ran her fingertips across a large white
mound that rose several inches from the surface of the bone-dry lakebed. As
a park ranger at the Great Salt Lake State Park
<https://stateparks.utah.gov/parks/great-salt-lake/> in northern Utah,
she’s accustomed to seeing the massive lake’s waterline recede, especially
during dry months when there’s little to no rainfall. However, over the
course of the last few winters, she and other rangers have noticed
something strange happening along the lake’s normally pancake-flat southern
shoreline, with large white lesions cropping up in areas that are normally
just sand.

“We were very concerned,” Anderson told me this spring. “One of our rangers
contacted the Utah Geological Survey looking for answers.”

Geologists from the UGS reviewed photos and took samples of the chalky
white heaps and concluded they’re piles of salt known as mirabilite mounds
<https://geology.utah.gov/popular/general-geology/great-salt-lake/mirabilite-spring-mounds/>,
or Glauber’s salt. These rare geological formations occur when underground
water reacts with minerals and burbles to the surface, intermingling with
the cold, winter air to form white crystals. Normally this portion of the
lake would be covered in water and wouldn’t be susceptible to this
phenomenon, however, for the last several winters, the fragile mounds have
become a common occurrence on the sandy lakeshore.

https://gizmodo.com/great-salt-lake-mirabilite-mounds-1849492129