Archive for Meteorite Identification

Meteorite ID

By · March 17, 2010 · Filed in Meteorite Identification · 3 Comments »

You are hunting and you find what you think is a meteorite. You want to be sure that you do not have a meteorwrong, so what criteria can you use to help you identify the object you have found? I am sharing some of that information with you so that you can try to deduce for yourself whether your find is something great, a meteorite, or something more common, like an terrestrial (Earth) rock.

Generally-speaking, a meteorite is a piece of stone, iron, or a mixture of stone and iron that has fallen from outer space and landed on Earth. They may come from various locations in space, including the asteroid belt between Mars and Jupiter. Sometimes they come from parts that used to be planets or asteroids. Other times, they come from the Moon, Mars, or comets.

When testing your find to see if it is a meteorite, you need your eyes and hands, and a good-quality magnet from a hardware store (a rare earth magnet is the best for testing),  and a little bit of important information.

First, take your magnet and see if it sticks to the suspected meteorite(even stony meteorites have a high content of iron).If the magnet doesn’t stick you probably don’t have a meteorite. But remember all meteorites rocks are magnetic but not all magnetic rocks are meteorites. Now feel the weight of your find. If it feels heavier and more dense than most terrestrial rocks you have encountered, this is an indicator that you might have a meteorite. Iron meteorites are approximately four times as heavy as a terrestrial rock of the same size; stone meteorites about three times as heavy.

Next, move onto a visual inspection. Meteorites have several noticeable features, such as:

  • A fusion crust: Fusion crust occur as the meteoroid was burning in the Earth’s atmosphere through a process called albation. Fusion crusts very somewhat because of the meteorites different materials.Fresh fusion crusts are a matte (dull) black, but some fresh meteorites have a fusion crust that looks like shiny black glass. Older meteorites that have been here long enough to weather or oxidize, the fusion crust turns from black to either brown, yellow, orange, or reddish appearance called Patina and will eventually disappear altogether. Many people think the crust as being like the skin on an orange, but it is much more like the skin on an apple, very thin.
  • Thumbprint – type markings called Regmaglypts caused by albation.(not all meteorites have these)
  • Flowlines caused by melting or albation.(not all meteorites have these)
  • Metallic flakes if the inside of an ordinary chondrite is visible.
  • Small, grainy spheres called Chondrules. (found in most stony meteorites)
  • Rust on meteorites that have been exposed to Earth’s elements for a long period of time.

Next, meteorwrongs  have several noticeable features, such as:

  • Small holes, called vesicles (these are often found on the surface of volcanic rocks, caused by gas as it escaped when the lava was cooling.
  • If the rock feels light it is not a meteorite.
  • Sharp pointed features (unless broken) are not found on meteorites.
  • A type of rock that people often mistake for meteorites are those composed of iron oxides like hematite and magnetite because such rocks are denser than most common rocks. Hematite and magnetite can be recognized by the streak test. Streak is a word referring to the color of the streak that a rock makes when it is scraped against the unglazed underside of an ceramic toilet tank lid or, the unglazed bottom of a white coffee cup. Hematite makes a rust or blood-red colored streak; magnetite makes a dark gray streak. Hematite and magnetite streaks are easy to make, almost like chalk on a sidewalk. Meteorites gives NO streak or only a weak grayish streak, but only if you press hard.

If you have completed these three tests, magnetic, weight, and visual and you are still unsure of your find, you may want to look into purchasing some additional resources. I have these books available in the Book Section of my online store that can help you with your identification:

  • Rocks from Space: Meteorites and Meteorite Hunters (by O. Richard Norton)
  • Field Guide to Meteors and Meteorites (by O. Richard Norton)
  • Meteorites (by Caroline Smith and Sara S. Russell)
  • Falling Stars: A Guide to Meteors and Meteorites (by Mike D. Reynolds)
  • Souvenirs from Space: The Oscar E. Monnig Meteorite Gallery (by Judy Alter)
  • Meteors and Meteorites (by Gregory Vogt)

Here’s to the perfect hunt!