The Campo del Cielo is classified as an IAB coarse octahedrite. It exhibits many beautiful characteristics, unique to meteorites, including regmaglypts, thumbprint-like surface features caused by a meteorite melting during its fiery journey through Earth’s atmosphere. The pure iron asteroid hailed from the Main Asteroid Belt located between Mars and Jupiter, and split up over an area of 60 square kilometers when it crashed to Earth 4,000–5,000 years ago. It is the heaviest meteorite so far recovered on the planet, at over 100 tons, and the largest fragment of 37 tons, known as ‘El Chaco’, is second in size only to the Hoba meteorite in Namibia. A fragment weighing 1,398 lbs was donated to London’s Natural History Museum.
In 1576, the Spanish governor of a province in northern Argentina sent a military detachment to search for a large mass of iron, having heard that the local natives were using it for weapons, and claimed that it had fallen from the sky. The governor reported the discovery of a large mass of iron protruding from the earth, of unusual purity and assumed to be the tip of a seam, to the Archivo General de Indias in Seville, but the find was soon forgotten. In 1774, Don Bartolome Francisco de Maguna rediscovered the iron mass, having become fascinated by legends of the local inhabitants, and called it ‘the Table of Iron’. In 1783, Rubin de Celis cleared the ground with explosives and found that it was a single mass, not the seam of a mine. He sent samples to the Royal Society in London, who declared it a meteorite, something Celis had failed to realize.
In 1990, a local Argentinian highway police officer foiled a plot by Robert Haag to steal El Chaco. It had already been moved out of the country, but was returned to Campo del Cielo, and is now protected by a provincial law.