A large loose gem twinned crystal of colorless glassy gypsum. This is in very good condition for one of these with just slight micro-damage present. The specimen comes with a previous label from the collection of Ray DeMark who acquired the piece while in Naica in 1976.The Naica mining district in Chihuahua, Mexico, originated with its first recorded claim in 1794, transitioned through intermittent operations and modern industrial development by companies like Industrias Penoles, and suspended operations indefinitely in October 2015 due to uncontrollable underground flooding. Geologically, the deposit sits within an Early Cretaceous carbonate sequence of limestones and dolostones intruded by a hidden magmatic body. This intrusive heat source maintained a deep, mineral-saturated thermal aquifer for hundreds of thousands of years, driving hydrothermal ore deposition (lead, zinc, and silver) as well as the specialized dissolution and recrystallization cycle that formed the world-famous giant selenite gypsum crystals found within its underground cavities.
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