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Naica, Chihuahua, Mexico

 

Nobody would have known that the mine of Naica is the principle producer of lead in Mexico, if it were not famous for its crystal caverns. Today, it is known for this wonder of nature that has been found 300 metres underground. Here, the crystals, which measure up to 11 metres and weigh up to 55 tons, are the largest crystals ever to have been found on the entire planet. However the mine of Naica is in itself very important. Not only does it produce significant amounts of silver and lead, it is one of the most important locations in Mexico for its fine mineral specimens worthy of any museum or private collection.

The town of Naica is situated a little to the south of Chihuahua, in the municipality of Saucillo. Its name is derived from the tarahumara word which means “shady place”. This place has been dedicated to mining since 1794. Its golden age began in 1828, when Santiago Scopelli found the first mineral deposits. As a result of this discovery, the Compañia Minera Naica S.A. founded the town for the exploitation of the minerals. Even though the success of the mining town was magnificent, its growth was paralyzed and the town practically abandoned, at the onset of the revolution. By 1925, the economy of the country was recovering under the new regime and several companies continued extracting minerals. In 1951, The Company Fresnillo, part of the Mexican company Peñoles, acquired the mine and began modernization. They installed electric pumps to drain water from the excavation, and within a year they had doubled production capacity. Their work in the field of mining continued to grow and today it is the most productive mine in the state of Chihuahua.

The entire mining zone is made up of a complicated system of mantles and interconnected chimneys, of between three and 70 metres in diameter that descend to almost 700 metres in depth. The mineralization of the area is generally composed of sulphur minerals such as: galena, spharelite, pyrite, and in smaller quantities, chalcopyrite, pyrrohtite, bournonite and silver sulphates. Fluorite is abundant in three levels, together with a countless number of species such as garnet, quartz, dolomite, vesuvianite and calcite. The fluorite of Naica has been appreciated for years for its characteristic pale green colour that resembles green apples.


The crystal cavern was discovered in 2000 by two brothers who were excavating for minerals hundreds of metres below the surface. They were greatly admired for their finding what seemed to be a landscape right out of a dream. It was a cavern full of enormous crystals of selenite, a whimsy of nature that looked like a scene from a science fiction movie.
The temperature in the mine of Naica rises gradually the deeper one goes down. This is due to the mine’s location which is directly above a magma intrusion located approximately one mile below surface. Inside the crystal cavern the temperature is 50 degrees centigrade with a humidity level of 90%. Scientists and explorers who enter this cavern must wear appropriate protective clothing.

SeleniteLuis Lyons photo

CalciteSeleniteLuis Lyons photos

The crystals are of selenite, a type of common gypsum that is soft and translucent. Selenite is so easy to cut that a single fingernail can cause it to indent. It would appear that it originated hundreds of thousands of years ago, when subterranean rivers, saturated with calcium sulphate, flowed to the area and filtered through the numerous caves in the region. The water was heated due to its proximity to the magma intrusion and as the magma cooled down the molecules of selenite in the water joined together in perfect order to form crystalline blocks. The water in the underground caves, enriched with sulphides of the adjacent metal deposits, began to dissolve the limestone walls liberating large quantities of calcium. This calcium in turn combined with the sulphides to form crystals of a scale never before witnessed by human beings. The largest of these crystals is calculated to be 600 thousand years old. The crystal cave has maintained the same conditions during thoUnited States of Americands of years whilst geographic events occurred externally, encouraging the crystals to grow without interruptions. It was not until 1985, when the massive powerful pumps of the mine drained the level of water in the excavation area, that the cavern was discovered.