Crystal Palace — Quiz — National Geographic Magazine

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Managing Editor, NGM.com Rob Covey <![CDATA[Producer]]> Paul Heltzel Flash Developer Stefan Estrada Styling Kitry Krause Story Editor Glenn Oeland Photo Editor Sadie Quarrier Researcher Taryn Salinas /2008/11/crystal-giants/img/crystal-cave-470.jpg Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/tent-shadow-470.jpg Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/descent-truck-470.jpg Researchers descend by truck through a serpentine mine shaft. Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/crystal-cave-explorers-470.jpg Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/shark's-mouth-cave-470.jpg The interior of a cave called the Shark's Mouth Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/ice-cooled-suit-470.jpg A researcher rappels down into the Cave of Crystals. Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/crystal-closeup-470.jpg Several minerals have been found here that have never been seen inside caves before, including such tongue twisters as plumbojarosite, szmikite, and szomolnokite. Photograph by Carsten Peter, Speleoresearch & Films /2008/11/crystal-giants/img/worker-machinery-470.jpg Inside the Naica mine, where excavations in 2000 led to the chance discovery of the giant crystals Photograph by Carsten Peter, Speleoresearch & Films 7 Excellent work. You win the crystal medal. With a little work, you will be a crystal giants pro. You are off to a good start. You may want to try again. 0 Nearly ten feet long and nearly one million years old More than 30 feet long and about half a million years old At least a hundred feet long and a thousand years old Fifty feet long; scientists are currently dating the crystals. 2 1 The extreme heat could be lethal. The cave sometimes unexpectedly floods. Breaking crystals could fall and injure the cavers. Exposure to calcium sulfate poses a serious health risk. 1 2 A team of British explorers in 1856 A mining company in 1962, during a massive collapse A team of geologists in 1920 Two brothers drilling belowground in 2000 4 3 Dolomite Selenite Quartz Calcite 2 4 Minerals in heated groundwater cooled, allowing crystals to form. Mineral deposits and massive pressure forged the crystals. An underground river stored deposits as the water level rose and fell. No one's certain why the crystals grew to such proportions. 1 5 Some of the crystals broke into pieces. The crystals stopped growing. Smaller caves were flooded. The cave nearly collapsed. 2 6 Thinner, denser crystals Heavier, longer crystals Different and smaller crystals Opaque crystal formations 3 7 The caves contain huge stores of gold. Naturalists prize the cave for its big troglobite population. The mine is known for its large lead and silver deposits. The caves are popular with eco-tourism adventurers. 3