Ancient Asteroid Iron — 127 lbs.

First found in Argentina in 1576, the Campo del Cielo hit the atmosphere at approximately Mach 26, giving it a finely-textured fusion crust of soft gun-metal gray, dramatically highlighted by sharp ridges and some of the distinctive “thumbprint” regmaglypts caused by pressure to the molten metal on its fiery descent to Earth. This one has a very unusual barbell shape, as it almost separated on entry.

This iron-nickel meteorite was the former molten core of some planet-scale body that collided in the early formation of our solar system. It resembles the deep interior of the Earth. Molten metallic cores produce powerful magnetic fields. When they cooled and crystallized, traces of magnetism were imprinted on the metallic minerals in the core. Iron meteorites stick to magnets and deflect compasses.

Campo del Cielo, Iron, IAB-MG, coarse octahedrite
Gran Chaco, Argentina 1576
It measures 18″ x 9″ and weighs 57.6kg

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. The Natives 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”). 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 reports on the area merely repeated the Native legends.

Following the legends, in 1774 Don Bartolomé Francisco de Maguna rediscovered the iron mass which he called el Meson 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 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.

A crater field of at least 26 craters was found in the area, indicating that a large body entered the Earth’s atmosphere and broke into pieces which fell to the ground. The size of the main body is estimated as larger than 4 meters in diameter. The fragments contain an unusually high density of inclusions for an iron meteorite, which might have facilitated the disintegration of the original meteorite. Samples of charred wood were taken from beneath the meteorite fragments and analyzed for carbon-14 composition. 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 age is estimated to be 4.5 billion years old, formed as part of the development of our solar system.