One of the procedures when completing a well here in the Imperial Valley, is to change over the well to a KCl solution (mixed to a specific gravity of around 9.2 lbs/gallon), this helps manage the clays in the formation and is heavy enough prevent the hot geothermal fluids from coming up the well bore. The real problem with this stuff is its cost, its not cheap. It is normally separated form NaCl and other minerals from salt domes and other sources of brine (my favorite is the basins seen from Dead Horse Point, Utah, even though it is rather disruptive to the scenery). Some care must be taken with it as it can interfere with electrical function of the heart.
This lump of claystone/siltstone was saturated with some of the solution in the well and was circulated out of the well bore. It started to dry in my petri dish and sprouted KCl hairs as the crystals nucleated on the surface of the clay. Pretty much formed these hairs in about 24 hours of exposure to air.
and just a pretty pick, here is Nabors 58, with some "sort of" noctilucent clouds.
the sun was already going over the mountains to the west.