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Sikhote-Alin Meteorite. Image Credit: Wikimedia User, Vesta
You may not know it, but there are several types of meteorites. Most people tend to think that meteorites are just lumps of metal that fell from the sky. However these are only one type out of the many different kinds of meteorites out there. We also have to take into account that the kinds we do know of are those that we have encountered on Earth. Conditions in other parts of the Universe and even in our own galaxy may produce other types beyond what we now know. Right now the main types of meteorites we know of are iron meteorites, silicate iron meteorites, stony iron meteorites, and stone meteorites.
Iron meteorites are one of the rarest types of meteorite. Only 10 percent reach Earth. At first glance they are easy to distinguish from ordinary rocks due to their metallic feel and appearance. In most cases they have a finely polished black outer layer due to the heat of entry into the Earth’s atmosphere. However this doesn’t hide its metallic nature from the casual observer. This type is also one of the rarest in space. This is because they are originally from the cores of asteroids and other celestial bodies with different layers of material. A key characteristic is the Windmanstatten geometric pattern produced when they are sawed in half and polished.
Silicated iron meteorites are similar to iron meteorites except there is also a lot of silicates mixed in. This kind of meteorite is lighter and has more a more mixed composition than normal iron meteorites. This mixing of different elements gives it unusual features. One such feature is unusual thumbprint-like indentations in the meteorite.
Stony iron meteorites are extremely rare. In most cases a meteorite will be composed largely of one element or another. This is largely due to the differentiated layers of the asteroids and meteors they originate from. In the case of stony iron meteorites, the stone can be normal stone or mineral such as the gem mineral olivine that mixes with the common iron. This type is highly prized by collectors.
One of the rarest types of meteorites is the stony meteorite. This type is common in space but is very rare on Earth due to how hard it is to find and distinguish from normal rocks. Stony meteorites are like normal rocks except for the weathering showing that they entered our atmosphere. This type is hard to find since it can erode quickly.
We have written many articles about meteorites for Universe Today. Here’s an article about where meteorites come from, and here are some meteorite photos.
If you’d like more info on meteorites, check out the NASA Solar System Exploration Guide on Meteors. Also, here’s an article about Sugar in Meteorites.
We’ve also recorded an entire episode of Astronomy Cast all about Meteor Showers. Listen here, Episode 8: Meteor Showers. Yes, the Sky is Falling.
Sources:
http://www.novaspace.com/METEOR/Types.html
http://www.astro.washington.edu/courses/labs/clearinghouse/labs/Meteors/meteors.html
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