- Thenardite, Mirabilite
- Small Cabinet, 7.8 x 6.4 x 1.8 cm
- Boron, Kramer District, Kern Co., California, USA
This is a rareCalifornia specimen, a pseudomorph of thenardite after mirabilite (a hydrous sodium sulfate mineral). Mirabilite is found around saline springs and along saline playa lakes, with thenardite and other evaporites. Ex. Jim Minette Collection.From Rock Currier: "Those specimens showing the long prismatic mirabilite were collected by Jim Minette from the settling ponds out west of the big open pit mine. They take the mud slurry from the million gallon plus round dissolving tanks that are used at the refinery to dissolve the crude borax ore and run it into the settling ponds to settle out the fine mud/clay particles. Any water that is not evaporated naturally, they run back through the system. Sometimes the water in these ponds is saturated with sulfate and under the right temperature conditions, usually early in the morning, crystals of mirabilite grow rapidly in the ponds, and in the ones that Jim collated the mirabilite grew in prismatic crystals. Some of these had a little "iron" in them, so when the crystals dried out they were pink in color. Jim would put them on the bank of the pond and when they dried enough he would take them home and spray them with Krylon plastic to preserve them."