Title: Formation of natural gypsum megacrystals in Naica, Mexico
Abstract: Research Article| April 01, 2007 Formation of natural gypsum megacrystals in Naica, Mexico Juan Manuel García-Ruiz; Juan Manuel García-Ruiz 1Instituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Científicas-Universidad de Granada, Campus Fuentenueva, E-18002 Granada, Spain Search for other works by this author on: GSW Google Scholar Roberto Villasuso; Roberto Villasuso 2Compañía Peñoles, Unidad Naica, Naica, Chihuahua, Mexico Search for other works by this author on: GSW Google Scholar Carlos Ayora; Carlos Ayora 3Institut de Ciències de la Terra Jaume Almera, Consejo Superior de Investigaciones Científicas, Lluis Solé Sabarís s/n, E-08028 Barcelona, Spain Search for other works by this author on: GSW Google Scholar Angels Canals; Angels Canals 4Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, Martí Franquès s/n, E-08028 Barcelona, Spain Search for other works by this author on: GSW Google Scholar Fermín Otálora Fermín Otálora 5Instituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Científicas-Universidad de Granada, Campus Fuentenueva, E-18002 Granada, Spain Search for other works by this author on: GSW Google Scholar Geology (2007) 35 (4): 327–330. https://doi.org/10.1130/G23393A.1 Article history received: 25 Sep 2006 rev-recd: 03 Dec 2006 accepted: 07 Dec 2006 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Juan Manuel García-Ruiz, Roberto Villasuso, Carlos Ayora, Angels Canals, Fermín Otálora; Formation of natural gypsum megacrystals in Naica, Mexico. Geology 2007;; 35 (4): 327–330. doi: https://doi.org/10.1130/G23393A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Exploration in the Naica mine (Chihuahua, Mexico) recently unveiled several caves containing giant, faceted, and transparent single crystals of gypsum (CaSO4•2H2O) as long as 11 m. These large crystals form at very low supersaturation. The problem is to explain how proper geochemical conditions can be sustained for a long time without large fluctuations that would trigger substantial nucleation. Fluid inclusion analyses show that the crystals grew from low-salinity solutions at a temperature of ∼54 °C, slightly below the one at which the solubility of anhydrite equals that of gypsum. Sulfur and oxygen isotopic compositions of gypsum crystals are compatible with growth from solutions resulting from dissolution of anhydrite previously precipitated during late hydrothermal mineralization, suggesting that these megacrystals formed by a self-feeding mechanism driven by a solution-mediated, anhydrite-gypsum phase transition. Nucleation kinetics calculations based on laboratory data show that this mechanism can account for the formation of these giant crystals, yet only when operating within the very narrow range of temperature identified by our fluid inclusion study. These singular conditions create a mineral wonderland, a site of scientific interest, and an extraordinary phenomenon worthy of preservation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.