National Geographic has online an article about Cueva de los Cristales – a cave of huge natural crystals. The crystals were exposed by mining operations which pumped water out of the cave. It sounds like the crystals will fall apart if the water is not allowed to refill. It\’s unclear how long before the crystals diminish, or if they will be preserved. Refilling the cave of course means that people wouldn\’t be able to see the crystals. Maybe they could let it refill and pump it out for a few months every few years or something? The photos on that article page are amazing.