Giant selenite crystals - some more than 35 feet long - are found in Mexico's Naica mine caverns.
For millennia, hot, mineral-rich water filtered through the cave at just the right temperature for crystals to form. They grew undisturbed until 1985, when miners pumping out adjacent mines unknowingly drained the water from the cave. No longer immersed, the crystals stopped growing.
The water is gone, but conditions in the caves are still extremely humid with temperatures reaching 112 degrees. Even with protective clothing, a visit of more than 20 minutes carries the risk of heat stroke.
Natural History Museum in Balboa Park, San Diego Featuring "ALL THAT GLITTERS" - The Splendor & Science of Gems & Minerals.
***Photos taken without flash through glass/plexiglass
Balboa ParkSan DieogGemMineralshowAll that glitters