Meteorites are thought to originate from the disintegration of one or more planets similar to the Earth in composition but smaller, perhaps in the form of a small asteroid. A few meteorites may have even originated on the Moon or Mars.
There are three types of meteorites: irons, stony irons, and stones.
Tektites are glassy meteorites which are in fourth class. Tektites are fundamentally different from the three main types.
The iron meteorite in the images is a Campo del Cielo meteorite. Campo del Cielo means "field of the heaven."
The weight of this specimen is 7.6 lbm. It is an iron alloy with some nickel, cobalt and other elements.
The black crust on the meteorite in the images is iron oxide. Many iron meteorites have a layer of rust.
The small indentations are referred to as "thumb prints." They are caused by melting during entry into the Earth's atmosphere.
Iron meteorites are composed of two mineral alloys, kamacite and taenite.
Kamacite is an alloy consisting of iron with 5% to 7% nickel. Taenite is an alloy consisting of iron with 13% or more nickel.
Meteorites may be sliced to show the internal cross-section. The cross-section can be polished and etched with dilute acid. This process usually reveals bands of kamacite and taenite. Iron meteorites are further classified depending on the width of these bands and the angle at which they meet. Two subclasses are octahedrites and hexahedrites.
Campo del Cielo meteorites are described as a polycrystalline coarse octahedrite, Group I. These meteorites came from a "strewn field" that was first discovered in 1576 by Spanish explorers in Chaco, Argentina.
Scientists have found numerous pits and impact craters in this area. The impact occurred between 3950 and 5800 years ago, based on dating of charred wood found in the craters. Scientists speculate that these meteorites were part of a single meteorite that broke up upon entering the Earth's atmosphere.
A Spanish governor learned of the iron from the Indians who reportedly believed that it had fallen from heaven. The governor sent an expedition under the command of one Captain de Miraval who brought back a few pieces of a huge iron mass he called Meson de Fierro, which means "large table of iron."

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