Giant hydrothermal gypsum crystals growing at a mixing interface with the meteoric-phreatic realm скачать в хорошем качестве

Giant hydrothermal gypsum crystals growing at a mixing interface with the meteoric-phreatic realm

Some of the most visually striking examples of hydrothermal gypsum precipitation occur in the Naica mine in Chihuahua, Mexico. There several natural caverns, such as Cave of Swords (Cueva de la Espades discovered in 1975) and Cave of Crystals (Cueva de los Cristales discovered in 2000), contain giant, faceted, and transparent single crystals of gypsum as long as 11 m. Crystals in Cueva de los Cristales are the largest documented gypsum crystals in the world. These giant crystals grew slowly at very low supersaturation levels from thermal phreatic waters with temperatures near the gypsum-anhydrite boundary. Gypsum still precipitates today on mine walls. According to García-Ruiz et al., 2007, the sulphur and oxygen isotopic compositions of these gypsum crystals are compatible with growth from solutions resulting from the dissolution of anhydrite, which was previously precipitated during late hydrothermal mineralisation in a volcanogenic matrix.  Another set of meter-scale giant gypsum crystals occurs in the Pulpí Geode in the Mina Rica Mine in Spain. The Pulpí and Naica locations are examples of non-evaporite salts, and both form via the uplift of a sulphide-rich hydrothermal system into the telogenetic realm. This video chapter from Saltworks' upcoming online evaporite course discusses the nature and distribution of these hydrothermal salts and examines whether they can be classified as a form of evaporite salt. For a digital version of portions of this content, visit https://saltworkconsultants.com/hydro...