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818 Views 7 Replies Last post: Mar 31, 2013 9:23 PM by MikeHardman RSS
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Mar 31, 2013 9:27 AM

Is this a meteorite

Photo0651.jpg

This was found in Hout Bay in Cape Town 1989 by my son. it is heavy and appears to be almost solid iron sort of rock. Many years ago I took it to the planetarium in Johannesburg, and they said it could be a metorite. I would like to have some others opinion on this rock that I have kept safe over these years.weight of the stone is 550grams. and there are no sharpe edges on it.

Many thanks

Carolyn Dewrance

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    Mar 31, 2013 10:56 AM (in response to Carolyndewrance)
    Re: Is this a meteorite

    Carolyn,

     

    ...Maybe...

     

    It would be useful to know its density (can compare it with the list of densities in the middle link below).

    Calculate its volume by immersion in water. For instance:

    1. put one container in another one, fill the middle one with water (carefully, to the brim)

    2. carefully (perhaps using a cradle made of thin wire or string) put the specimen in the middle one (overflow goes into outer container)

    3. remove middle container without spillage

    4. measure volume of water in outer container.

    Then density (g/ml) = mass (g) / volume (ml). [ml = cubic cm]

    That will give a figure that is good enough for our purposes, though it does not take account of factors such as absorbency of the specimen.

     

    Then have a look at these:

    - http://www.nhm.ac.uk/natureplus/community/identification/blog/2012/08/15/rocks-from-space--have-you-found-a-meteorite

    - how to identify a meteorite - http://epswww.unm.edu/iom/ident/index.html

    - http://www.meteorites.com.au/found.html

     

    Regards,

    Mike

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    Mar 31, 2013 5:02 PM (in response to Carolyndewrance)
    Re: Is this a meteorite

    550g/90ml = 6.1g/ml

    That makes it lighter than average for an iron meteorite (8g/ml in the table I referred to), but more dense than iron ore (haematite, 5.1g/ml).

    So I suspect it is largely iron, but with impurities (metallic or non-metallic).

    It could be man-made or it could be a meteorite

    That's a start. See how you get on with the other links.

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      Mar 31, 2013 9:23 PM (in response to Carolyndewrance)
      Re: Is this a meteorite

      Re: 'What else must I do to test this lovely rock?'

       

      Follow the guidance in the links in my first reply.

      We're looking for a 'body of evidence' ID. That is, there are many things that can be checked, and the more 'meteorite' boxes that are ticked, the greater the liklihood that it really is a meteorite; and the more non-meteorite boxes, the lesser the liklihood of it being a meteorite.

      Fusion crust, regmaglypts, iron-nickel metal and magnetism (OK, you've confirmed neither of those apply), density (3.1 is on the light side for a stony meteorite, but yours is only an estimate of its true density), chondrules (you'd probably have to break or saw off a corner to look for these), streak. ...All as in that web page. No point in me copying it here.

       

      Keep in mind the general alternatives: If not a meteorite, your specimen would probably be a natural stone (such as basalt) or a man-made object (such as smelting waste). And in a beach environment, you could find either, since cargo/ballast from wrecked ships can end up there, and rocks and rock-like materials can be added by man to beaches to help control coastal erosion.

       

      Stellenbosh will look at your specimen the same way, and may ask you if they can cut it to look for internal structure (chondrules, eg.) They may also want to make a thin section so they can observe its minerals under the microscope.

       

      You could also try contacting Jeff Kuyken, the author of the last link (http://www.meteorites.com.au/found.html); read the last paragraph on that page.

       

      I wish there was an easier way for you to get the answer.

      Regards,

      Mike

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