The Morning News https://ift.tt/2J8GWgv
Researchers have determined how the world's largest geode grew to its massive size of 11 cubic meters:
Although the cave is now dry, when the geode was growing, its cavity was filled with hot, mineral-rich water. The oldest layer of crystals, which include the mineral barite (barium sulfate), formed at temperatures of about 100°C. Subsequent layers, which include crystals of celestine (strontium sulfate), grew in waters somewhere around 70°C. The youngest crystals of gypsum (hydrated calcium sulfate) formed at temperatures of about 20°C at least 60,000 years ago—well before the coldest part of the last ice age.
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