CAMPO DEL CIELO
Campo del Cielo refers to a group of iron meteorites and to the area in Argentina where they were found. The site straddles the provinces of Chaco and Santiago del Estero, 1,000 kilometers (620 mi) north-northwest of Buenos Aires, Argentina.
The results indicate the date of the fall to be around 4,200–4,700 years ago, or 2,200–2,700 years BC.
The average composition of the Campo del Cielo meteorites is 6.67% Ni, 0.43% Co, 0.25% P, 87 ppm Ga, 407 ppm Ge, and 3.6 ppm Ir, with the remaining 92.6% being iron.
In 1576, the governor of a province in Northern Argentina commissioned the military to search for a huge mass of iron, which he had heard that natives used for their weapons who claimed that the mass had fallen from the sky in a place they called Piguem Nonralta which the Spanish translated as Campo del Cielo ("Field of heaven (or the sky)"). The expedition found a large mass of metal protruding out of the soil. They assumed it was an iron mine and brought back a few samples, which were described as being of unusual purity. The governor documented the expedition and deposited the report in the Archivo General de Indias in Seville, but it was quickly forgotten and later local reports merely repeated the Native legends.
Following the legends, in 1774 Don Bartolomé Francisco de Maguna rediscovered the iron mass which he called el Mesón de Fierro ("the Table of Iron"). Maguna thought the mass was the tip of an iron vein. The next expedition, led by Rubin de Celis in 1783, used explosives to clear the ground around the mass and found that it was probably a single stone. Celis estimated its mass as 15 tonnes and abandoned it as worthless. He himself did not believe that the stone had fallen from the sky and assumed that it had formed by a volcanic eruption. However, he sent the samples to the Royal Society of London and published his report in the Philosophical Transactions of the Royal Society. Those samples were later analyzed and found to contain 90% iron and 10% nickel and assigned to a meteoritic origin.