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El Boleo, Santa Rosalía, Baja California Sur, Mexico
In the peninsular of Baja California copper mining completely revolutionized the economy of the region, substituting its agricultural tendencies with a successful mining community.
Before the arrival of the mining companies there had been an ambiance of precariousness and a shortage of goods, on account of the remoteness of the towns. The development of the mining industry was the driving force that changed the image of the area as being a remote desert, to one of mineralogical importance. In El Boleo mine in the region of Santa Rosalía, three types of boleite were discovered, boleite, pseudoboleite and cumengeite. These minerals have since been found in 20 other locations throughout the world. Specimens of these minerals are highly prized by collectors for their colour and unusual habits. They are without a shred of doubt the most curious and extraordinary minerals in the world.Specimens of these minerals are highly prized by collectors for their colour and unusual habits. They are without a shred of doubt the most curious and extraordinary minerals in the world.
El Boleo is located in an arid area; it was there, in 1868, that José Rosa de Villavicencio discovered in the desolate hills between the forest of cacti and the sea, a mineral which could be crumbled by hand. The pieces were round in shape giving rise to their name ‘boleos’. Samples of this strange finding were sent with a sailor to Guaymas to be analysed by a specialist. He was greatly surprised when the results came back identifying the specimen as copper of good quality. The dream of riches attracted many miners and explorers to the area until 1872, when the Eisenmann and Valle negotiations began. In 1885, the mines became the property of the company El Boleo, a company founded in France. The arrival of the French was fostered by a modification of article number 72 of the Mexican Constitution. In addition, a new mining code offered mining concession rights to foreign investors. President Porfirio Díaz published a decree that authorized the new company to be exempted from paying taxes and that allowed it to export all the copper it wished to for a period of 50 years. In return, the company was obliged to build a town and employ all the Mexicans who applied for work there. In less than a year they built the town they named Santa Rosalia and the company adopted the name El Boleo after the spherical shape of the deposits of copper. By 1900, the company contributed nearly 90%, the major part of the copper production of Mexico. Edouard Cumenge carried out the first mineralogical studies of the area in 1893. He was a geologist who was the advisor of the mining company and an avid collector of mineral specimens. His studies were extensive, encompassing all the new specimens found in Boleo. He noted the unusual cubic shape some of the specimens acquired and the star shapes of the cumengite, whose characteristic deep indigo blue makes them so valuable


Luis Lyons photo

It is incredible that the first specimens found back in the X1X century, are still the motive of admiration and continue to appear in sales of private collections. The number of specimens found is quite modest, since they were only found in the Amelia mine. Cumenge carried out various chemical analyses on the indigo coloured cubes he found and discovered that their composition was very similar to that of percelit, even though they had inclusions of silver. In his crystallographic analysis he found three distinct forms: cubic, octahedral and dodecahedral protruding from pyramids in the form of a star. The unusual habits of these minerals have caused a great deal of controversy amongst scholars and given rise to innumerable essays. Some investigators have believed that they would find an example of clusters with true fragments of metallic structures.

BoleiteLuis Lyons photo

The copper deposit in the Boleo zone is on the east coast of Baja California very close to the manganese mantle known as Lucifer. It covers an area of around 200 square metres, the mineral deposits of the area were formed in the Pliocene and the Pleistocene periods, during which time there were volcanic events and tectonic movements that formed the mineral beds. There is very little left of the volcanic region today, but it was due to that series of events that the copper rich veins were formed.
Santa Rosalia still maintains the image although slightly modified, that the French gave to and maintained until 1954 when they closed the mine and abandoned the city. The Town Hall and Post Office are situated in buildings that resemble those of the colonies in Guadalupe or Martinique, with their galleries covered by a small roof. In their surroundings the homes of the hierarchy of El Boleo were built. It is there where the new directors of the Minera Boleo, a Canadian Company that proposed the reopening of the copper mine, now live. A few years ago, a South Korean led consortium purchased 30% of the mine. It has been estimated that the mine still contains some 277 tons of copper that would give an annual production of 41 tons and would last for at least 24 years. This demonstrates that Mexico, despite almost 50 years of exploitation, still holds a successful future.