Playa lakes are features that develop in low-lying areas of enclosed basins. Because water carries dissolved ions into the lake basin but not out (the water leaves by evaporation), the lakes become quite salty. Sometimes they dry up, to become salt flats, or merely “playas.” Occasionally, there’s good stuff in these briney lowlands. That’s the case at Trona, California, on the shores of Searles Lake, a lake that is partially wet…
… and partially dried out into a massive salt flat:
What were we out here to see? Well, it’s always cool to walk out into wide open spaces, particularly with the crunch of salt under your boots, letting you know something fundamental about the hydrology of the area…
…Also, there were giant crystals of hanksite (KNa22(SO4)9(CO3)2Cl). This is the place where hanksite was first described, and where it is most common in the world:
There were also evaporating ponds that produced halite (NaCl):
Here’s a mostly-dissolved halite crystal with growth layers:
Salt flats with dessication cracks:
Up close, you can see the characteristic 120° angles at which these fractures meet, as well as the “teepee” structures that can form due to subsequent expansion:
Lastly, consider these two lovely crystals of sulfohalite (Na6(SO4)2FCl) that Erik found:
You find the largest crystals if you wade in the coldest pools.
Are these crystals hanksite or pseudomorphs of hanksite? Certainly the white powdery material on the surface is not hanksite, but a result of its dessication. I have tincalconite psuedomorphs of borax from Searles Lake that are white like your crystals.
They’re hanksite all right — that’s just a surficial salty powder. We scrubbed it off with brine, and the underlying crystal is transparent / translucent clear, with tinges of yellow gray.
Fair enough! Very different from borax, which was totally replaced. Thanks for an interesting blog!
Is it open to the public to take these crystals? Legal? Thinking about checking it out!
Collecting is permitted, but access is restricted. Check in with the mineral club in Trona.
Hello, we are students of Geology, National University of Cordoba Argentina Republic. we are doing a job and ephemeral lake systems and looking structures that form in these systems gave your blog .. doubt we have and we need to work on nuetro is like teepees formed?
From already thank you very much ..