Learn About the Allende Carbonaceous Chondrite Meteorite

Basic Information

  • Location: Pueblito de Allende, Chihuahua State, Mexico. Latitude 26 degrees 58 minutes North, Longitude 105 degrees 19 minutes West.

  • Type: Carbonaceous Chondrite, CV3.

  • Time of Fall: February 8, 1969, 01:05 local time.

    Where Allende Fell

    Here is a map (redrawn from Rocks from Space by O. Richard Norton) showing the location of the Allende fall:

    The "Allende strewn field" is the area where the meteorites were found. The long line with the arrow is the direction of the flight of the meteorite. (The curvy line is the highway.) The meteorite is named after the small nearby town of Pueblito de Allende (shown as Allende on the map).

    Like many meteorites, The Allende entered the atmosphere and friction began to heat it up. The main mass of the meteorite exploded and the fragments fell over the area shown as the "Allende strewn field." (If you use a Netscape web browser, you can get an idea how meteorites explode when they enter the atmosphere. Watch the little icon in the upper right hand corner. This is not a bad representation.) The strewn field is estimated to be more than 60 square miles.

    When Allende Fell

    The Allende meteorite fell at 1:05 AM on February 8, 1969. It created a huge fireball, then shattered and rained fragments over the area of the strewn field.

    How Big Was Allende?

    Allende is estimated to be several tons. Two tons were collcted after the meteorite fell, but specimens are still being found. It is possible that an accurate estimate may never be known.

    Allende's Composition

    Carbonaceous chondrites are thought to be the most primitive form of matter in the universe. Scientists theorize that if, at the beginning of time, the universe cooled and the dust clumped together and formed a rock, then the result would be something like a carbonaceous chondrite. You can learn more about the formation of chondrites by clicking here. CI carbonaceous chondrites--a somewhat more primitive type--have a composition very close to that of the Sun.

    The matrix or fine grained part of the Allende is primarily iron rich olivine. The total iron content is around 24 percent, but flecks of iron-nickel are only rarely found.

    Allende carbonaceous chondrites have another interesting feature. White clumps of white material--many with finger-like projections--are found throughout the meteorite. When analyzed these are mixtures of high temperature oxides and silicates of calcium, aluminum and titanium. They have been named calcium-aluminum inclusions, or CAIs for short. Scientists believe that these are among the first matter to have crystallized. They are older than the Earth itself. (The green arrows in the picture point to CAIs. The red arrows point to chondrules.)

    Scarcity of Allende Carbonaceous Chondrites

    Before the Allende fall, CV3 carbonaceous chondrites were very rare--only 16 falls are known today. (Click here to get an idea of how many of each kind of meteorite have fallen.) CV3s are still rare, but now we have the Allende samples.

    Carbonaceous Chondrites and Life on Earth

    Some have speculated that because of the carbon in this meteorite, it was somehow associated with extraterrestrial life or with the arrival of life on Earth. Chemical analyses of carbonaceous chondrites have revealed both non-biological and biological amino acids--the buildings blocks of life. Some of these amino acids are not found on earth.

    The implications of this discovery are twofold. First, the presence of these extraterrestrial amino acids suggests that extraterrestrial life is a real possibility. Second, if amino acids arrived on modern meteorites, then why not on earlier ones--and perhaps they had more than just the building blocks of life. This latter theory is not accepted by many scientists--but it is fun to speculate.

    Find Out More About Meteorites

    These books will help you learn more about meteorites:

    Rocks from Space by O. Richard Norton, Mountain Press, 1994. This book covers just about every aspect of meteorites in a way that the layman can easily understand.

    Meteorites by Robert Hutchinson & Andrew Graham, Sterling, 1993. A book with lots of pictures and answers to many fascinating meteorite questions.

    Meteorites & Their Parent Planets by Harry McSween, Cambridge U. Pr., 1987. Well written book for a layman with a technical background.

    Handbook of Iron Meteorites by Vagn Buchwald, U. of California Press, 1976. A very complete technical description of known iron meteorites.

    Let's Investigate Magical, Mysterious Meteorites by Madelyn Carlisle, Barron's, 1992. A well-done book for children-but written in a way that even adults will learn from it.

    To see our meteorite classification table and learn about the types of meteorites, click here.

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