This is comparable to temperature records in Death Valley, but with much wetter air that condenses in the lungs and prevents cooling via sweating.

As of October 2015[update], the mine had reflooded and the cavern filled once more with the water rich in minerals required for the crystals to grow.

[8] In 1910, miners discovered a cavern beneath the Naica Mine workings, the Cave of Swords (Spanish: Cueva de las espadas).

Special caving overalls were fitted with a mattress of refrigerating tubes placed all over the body and connected to a backpack weighing about 20 kilograms (44 lb) containing a reservoir filled with cold water and ice.

Stein-Erik Lauritzen (University of Bergen, Norway) performed uranium-thorium dating to determine the maximum age of the giant crystals, about 500,000 years.

[13][14][15] A team led by A. E. S. Van Driessche directly measured the growth rates of these giant gypsum crystals using present-day water of the Naica.

[16] Penelope Boston (New Mexico Institute of Mining and Technology, USA), speleologist and geomicrobiologist specialist of extremophile organisms, realized sterile sampling of gypsum drillcores by making small boreholes inside large crystals under aseptic conditions.

The aim was to detect the possible presence of ancient bacteria encapsulated inside fluid and solid inclusions present in the calcium sulfate matrix from its formation.

At the 2017 meeting of the American Association for the Advancement of Science, researchers, including Dr. Boston, announced the discovery of bacteria found in inclusions embedded in some of the crystals.

[17] Other researches covered the fields of palynology (pollen study), geochemistry, hydrogeology and the physical conditions prevailing in the Cave of Crystals.