Why Are Meteorites Metallic

Meteorites often contain metal.

Meteorites are natural objects created in outer space and do not burn up in our atmosphere when they reach the Earth. Meteorites located after being witnessed hitting the ground or entering the Earth’s atmosphere are called “falls.” Meteorites discovered after the event are called “finds.” To date, about 1,000 “falls” and 38,000 “finds” have been documented, according to the United States Geological Survey’s Meteoritical Survey. Unlike Earth rocks, many meteorites contain iron.

Categories of Meteorite

Traditionally, meteorites have been divided into three categories. Stony meteorites are rocks similar to those found on Earth, iron meteorites are mostly made up of iron and nickel, and stony-iron meteorites contain large amounts of rock, iron and nickel. Modern classifications categorize meteorites based on their structure, mineralogy and chemical and isotopic composition.

Metal Meteorites

Metal meteorites often contain iron or a mixture of iron and nickel called iron-nickel. Most terrestrial rocks do not contain any iron or iron-nickel because early in Earth’s history, most of its iron-nickel sank to form the planet’s core, and any remaining iron-nickel has been oxidized or rusted during Earth’s long history. Earth’s atmosphere, which contains oxygen and water, is much more conducive to oxydization than space, so most extraterrestrial rocks still contain their iron or iron-nickel.

Identification of an Iron Meteorite (Extraterrestrial Origins)

If you find a rock containing iron or iron-nickel, it could be a meteorite. Many people who think they have found a meteorite based on its metal content have in fact discovered man-made metal. Even if it falls from the sky, it does not necessarily mean it has come from outer space. The United States Geological Survey’s Meteoritical Society noted that, in 1994, a man-made metallic rock fell from the sky and struck a car in Spain.

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Identification of an Iron Meteorite (Metal Content)

Some common terrestrial rocks contain minerals like pyrites or micahs, which can appear shiny and metal-like. The best way to tell if a rock is a meteorite is to use a magnet. If there are shiny bits in it and it is not magnetic, it is probably not a meteorite.

Famous Iron-Nickel Meteorites

Discovered in Oregon in 1902, the Willamette Meteorite is the largest ever found in the United States, according to the American Museum of Natural History. It weighs around 13,000 pounds and is 91 percent iron, 7.5 percent nickel and 1.5 percent cobalt and phosphorus. It is approximately 10 feet tall, 6.5 feet wide and 4.25 feet deep. The American Museum of Natural History, which displays the meteorite, estimates it’s at least a billion years old and could have fallen in what is now Canada and moved to Oregon as part of a glacier.