February 8, 2001 - Discovery News

The largest natural crystals on Earth have been discovered in two caves within a silver and zinc mine near Naica, in Chihuahua, Mexico, according to mine officials. Reaching lengths of over 20 feet, the clear, faceted crystals are composed of selenite, a crystalline form of the mineral gypsum.

"Walking into either of these caves is like stepping into a gigantic geode," said Richard D. Fisher, an American consultant with the mining company to develop the discoveries as tourist attractions.

Fisher said that most people can endure only a few minutes in the caves due to their high temperatures. The smaller of the two, which is about the size of two-bedroom apartment, is 100 Fahrenheit. The large chamber, which Fisher describes as the size of a Cathedral, is 150 F. Both are located approximately 1200 feet below the surface.

The mining company plans to air-condition the caves before opening them to the public next year, Fisher said. He adds that reducing the heat gradually will not harm the crystals.

The largest previously known crystals were found in the nearby Cave of the Swords, part of the same mine system. Some of these are now on display at the Smithsonian Institution. The local government and mine owners hope to avoid removing any of the new discoveries for museum displays or private collections, Fisher said.

While the mine company is currently limiting visitation of the caves to scientific experts, mineral hunters have destroyed locks and broken into the chambers twice since they were first opened by mining equipment last April. One man was killed when he attempted to chop out a gigantic crystal that fell from the ceiling and crushed him, according to Fisher.

"We need more onsite protection of mine caves," said geologist Carol A. Hill, co-author of the book Cave Minerals of the World, who calls the new discoveries "by far the largest selenite crystals I have ever heard of."

Hill applauds the tourism plan. "Without it, the mining company would probably destroy the caves. Museums have enough crystals," she said. "It's important to preserve discoveries like this where they occur."

Fisher and mine officials will display photographs and small samples of crystals from the new cave at the Tuscon Gem & Mineral Show in Arizona - which starts today and runs through the weekend - where they plan to organize a scientific study of the caves to take place in March.

Giant crystal cave discovered

So clear, you can read text through the crystals

June 12, 2000 - BBC

A gigantic cave of crystals has been discovered in an old silver mine in Spain.

The geode, which is eight metres (26ft) long and crammed full of gypsum prisms, has been put under police guard to prevent souvenir hunters from raiding the extraordinary natural phenomenon.

The geologist who announced the find, Javier Garcia-Guinea, wants to turn the site into a tourist attraction.

He told BBC News Online that up to 10 people could sit inside the geode - an object normally small enough to hold in your hands.

"Bending your body between the huge crystals is an incredible sensation," he said. "When I was young I dreamt of flying, but never to go into a geode internally covered with transparent crystals."

Rumours of the existence of a giant gypsum geode had been circulating among mineral collectors since December.

But it was only on 28 May that Javier Garcia-Guinea, from the Spanish Council for Scientific Research (CSIC) in Madrid, finally managed to track down the cave.

"The crystals are absolutely transparent and perfect," he said. The geologist has searched the international literature and can find no other object to compare in size.

The geode - essentially a rock cavity which has become lined with crystalline deposits - is eight meters in length, 1.8 metres wide and 1.7 metres high (26 feet by six by six).

The crystals of gypsum - hydrous calcium sulphate - are about half a metre in length.

Javier Garcia-Guinea is concerned about theft

The giant geode may have formed at the same time as a geological event called the Messinian salinity crisis. At this time, about six million years ago, the Mediterranean Ocean evaporated, depositing thick layers of salts. The same, salt-saturated fluids could have filled up the Spanish geode, which lies near the coast.

The drying out of the Mediterranean was probably caused by a restriction in the straits of Gibraltar, the sea's only connection with rest of the Earth's oceans.

Javier Garcia-Guinea has blocked the entrance to the geode with five tonnes of rock and called in the police to guard the location. After a period of scientific study, he hopes the cave can be turned into a major local tourist attraction.

"The next possibility is to drill a hole to fix a window in the geode to show the tourists. Almeria is little town with nice beaches just four kilometres from the mine and is well known to English holidaymakers."