A paper about the formation of the spectacular gypsum crystals of the Cueva de los Cristales (Cave of the Crystals) of Naica (Mexico), supervised by Professor Juan Manuel García-Ruiz, of the Instituto Andaluz de Ciencias de la Tierra (Andalusian Institute of Earth Sciences) of the University of Granada (Spain) has been included in the last edition of the McGraw-Hill Publishing House’s Yearbook of Science & Technology 2008. This volume, edited for the first time in the year 1962, collects the 135 scientific papers on the most significant advances in science and technology (geology, genetics, astronomy, biomedicine, cell biology, climatology, etc) of social interest.
The paper published in the Yearbook explains the formation of the spectacular gypsum crystals of the Cave of the Crystals of Naica (Mexico). In 2006, the journal «The Geological Society of America» pointed out for the first time the geological conditions that allowed the formation of these giant selenite columns – up to eleven meters in length – which can be localized 290 metres deep.
The study, supervised by Professor García-Ruiz, also has the participation of Fermín Otàfora, of the Andalusian Institute of Earth Sciences; Carlos Ayora, of the Jaume Almera Institute of Earth Sciences-CSIC (Instituto de Ciencias de la Tierra Jaume Almera-CSIC); Àngels Canals, of the Department of Crystalography, Mineralogy nad Mineral Deposits of the University of Barcelona (Spain); and Roberto Villasuso, of the Compañía Peñoles company, Mexico.
The Cave of the Crystals
The Cave of the Crystals is in the mine of Naica, a deposit worked by the Compañía Peñoles company, in the Mexican desert of Chihuaua. It is a 30 metres long and and 10 metres wide cave, accidentally discovered in the year 2000 by a group of miners during their exploration works.
According to the authors, the crystals grew within very narrow ranges of temperature and chemical composition thanks to a stable mechanism of self-feeding that dissolved part of the mine’s anhydrite (anhydrous calcium sulfate), which precipitatd in gypsum. The giant crystals formed in a cave flooded with water in conditions of slight gypsum saturation and with anhydrite subsaturation (anhydrous calcium sulfate).
At a temperature around 58 ºC, the solubility of both minerals reachs the same level; at a lower temperature, anhydrite gets dissolved and gypsum precipitates (selenite) and that is the origin of macrocrystals. To start this process, it was necessary to save a very high energetic barrier, and therefore there were very few nucleation points. The system has remained stable for a long time to allow this this self-feeding.
This work was published by the journal National Geographic in November of 2006, and has been one of the most visited papers in the web page of this publication since then. In addition, it appeared in the cover of the renowned scientific journal «Geology».
Reference:
Juan Manuel García-Ruiz. Andalusian Institute of Earth Sciences of the University of Granada.
Tel: 958750599.
E-mail.: juanma.garciaruiz@gmail.com