This is kinda cool for folks who grew up watching" journey to the center of the earth" ( no "survival" implications): http://www.dailymail.co.uk/sciencet...ystals-discovered-1-000ft-Mexican-desert.html Pictured: The Cave of Crystals discovered 1,000ft below a Mexican desert By Victoria Moore Created 10:15 PM on 27th October 2008 Comments (24) Add to My Stories Until you notice the orange-suited men clambering around, it's hard to grasp the extraordinary scale of this underground crystal forest. Nearly 1,000ft below the Chihuahua Desert in Mexico, this cave was discovered by two brothers drilling in the Naica lead and silver mine. It is an eerie sight. Up to 170 giant, luminous obelisks - the biggest is 37.4ft long and the equivalent height of six men - jut across the grotto like tangled pillars of light; and the damp rock of their walls is covered with yet more flawless clusters of blade-sharp crystal. Scroll down for more Enlarge Crystal forest: People clambering through the Cave of Crystals in Mexico wearing suits and backpacks of ice-cool air to cope with the 112F temperature The giant obelisks are formed from groundwater saturated in calcium sulphate which filtered through the cave system millions of years ago They are formed from groundwater saturated in calcium sulphate which, warmed by an intrusion of magma about a mile below, began filtering through the cave system millions of years ago.