CUEVA DE LOS CRISTALES

"...the crystals measured up to 12 meters long (over 36 feet) with a single crystal weighing approximately 55 tons....Millions of years ago, volcanic activity filled the mountain with anhydrite, a waterless form of gypsum. As magma eventually cooled, the anhydrite began dissolving, enriching cave waters and allowing gigantic crystals to form. Amazingly enough, the size of the crystals has no limit and given enough time will grow to even larger proportions."

Giant Crystals of Naica, Mexico