Naica Mine

Enormous gypsum crystals (CaSO
4 · 2 H
2O) in the most spectacular Naica cavern, found during mining. Note the size of the person at the bottom right for the scale.

The Naica Mine of the Mexican state of Chihuahua, is a lead, zinc and silver mine.[1][2] Located in Naica in the municipality of Saucillo, the Naica Mine is owned by Industrias Peñoles,[3] the world's largest silver producer.[4][5] Caverns discovered during mining operations contain gigantic crystals of CaSO
4 · 2 H
2O (calcium sulfate dihydrate, gypsum, also sometimes called selenite. Peñoles announced in October 2015 that it was indefinitely suspending operations due to uncontrollable flooding at the Naica Mine.[6]

The peak underground air temperature was 58°C (136°F) with 100% relative humidity, which rapidly exposed the visitors to hyperthermia hazard and caused breathing difficulties. Because of the heat, unprotected researchers could only stay up to 10 minutes inside the cave. Longer visits required the use of a special suit fitted with a cooling system (ice reserve in a backpack with cooled water recirculating in polymer tubes installed over all the body surface) and delivering fresh air for easier breathing. The visits were limited to about half an hour, the time needed to melt the ice reserves.

  1. ^ García-Ruiz, Juan Manuel; Villasuso, Roberto; Ayora, Carlos; Canals, Angels; Otálora, Fermín (2007). "Formation of natural gypsum megacrystals in Naica, Mexico". Geology. 35 (4): 327. Bibcode:2007Geo....35..327G. doi:10.1130/G23393A.1. hdl:10261/3439.
  2. ^ Van Driessche, A. E. S.; Garcia-Ruiz, J. M.; Tsukamoto, K.; Patino-Lopez, L. D.; Satoh, H. (2011). "Ultraslow growth rates of giant gypsum crystals". PNAS. 108 (38): 15721–6. doi:10.1073/pnas.1105233108. PMC 3179101. PMID 21911400.
  3. ^ "The Naica Mina". Archived from the original on 25 November 2010.{{cite web}}: CS1 maint: unfit URL (link)
  4. ^ "Inicio". Industrias Peñoles (in Spanish). Retrieved 2024-05-04.
  5. ^ Maple mine, known also as Naica, "under Peñoles control since 1964.", Corporate mining operations, Retrieved June 15, 2019.
  6. ^ "Penoles suspends operations at Naica mine in northern Mexico". Reuters. 13 October 2015. Retrieved 14 October 2015.