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463 Views 3 Replies Last post: Jul 8, 2014 10:00 PM by MikeHardman RSS
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Jul 3, 2014 1:12 PM

Another "Rock or Meteor" question

Hi , after having this rock for over 40 years now i suspect its time to get advice on what exactly it is !

It has been in the family since the early 70's now i believe it was found around the High Peak/Derbyshire area

Ive tried to make the images as detailed/clear as possible

 

 

ANY help would be great !

 

Please see attached images:

Attachments:
  • Currently Being Moderated
    Jul 3, 2014 3:58 PM (in response to aps67)
    Re: Another "Rock or Meteor" question

    A curious specimen...

     

    If it is natural, I lean towards a volcanic rock with large, partly coalesced vesicles, though it is not a common appearance for such a thing. If it is man-made, I lean towards smelting slag,  I don't see anything to suggest meteorite.

     

    However, lets get a bit more info...

    I note the mass (738g). We could really do with the volume as well, in order to determine its density. That's best done by immersing it in water and noting the volume displaced. If you can do that, we'll make allowance for it including some cavities later.

    Magnetic properties: Is a paper clip attracted to it at all? Is a magnet attracted to it at all?

    Hardness: Can you scratch it with a knife? Will it scratch glass (try an old bottle)?

     

    Mike

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      • Currently Being Moderated
        Jul 8, 2014 10:00 PM (in response to aps67)
        Re: Another "Rock or Meteor" question

        So:

        - bulk density is 738/200 = 3.69g/ml (since there could be cavities, real density probably greater)

        - not magnetic in any way

        - hardness over 5.5, maybe over 6 (depends on the knife and the glass)

        - colour dark grey

        - lustre seems to be sub-metallic

        (I omitted asking you about its streak, silly me)

         

        I am ignoring the golden metallic areas, which clearly don't make up most of the volume.)

         

        There are few minerals that match, the most likely of which is tephroite, but that's still pretty unlikely

        - http://webmineral.com/data/Tephroite.shtml

         

        If it is an element rather than a mineral, the closest match for density is barium. But you wouldn't find that in its native form (which is silver-white so not a match anyway); it is too reactive with water and most non-metals. Within the elements, less close matches are also unlikely, for various reasons.

         

        There are various characters one can use to see if a rock is a meteorite, eg here

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

        You'll see that it starts off by stating: "Because of their high iron content, the vast majority of meteorites will attract a magnet." Your rock clearly fails that point. As you read through, you'll see there are several other meteorite  checkboxes it fails to tick.

         

        ...Which means it is either man-made, eg. slag.

        ...Or I've missed something.

         

        Whatever it is, it seems unusual to me; I have to suspect it is man-made.

        Because of the golden metallic surfaces, somewhat reminiscent of chalcopyrite, I suspect it is waste from metal smelting or other metal processing, quite possibly concerning copper and/or iron.

         

        Further analysis could be done in a lab.

         

        ...Not quite the answer you were hoping for, but I hope it helps in some way.

         

        Mike

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