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1072 Views 8 Replies Last post: May 8, 2013 1:28 PM by voodoo chile RSS
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Apr 3, 2013 1:43 PM

Rock found!

Hi

 

I found this many years ago when I was alot younger, even now we still wonder what it is, any ideas?

Many thanks, we had hoped it had fallen from space but thought it might simply be a bit of old iron.

Adam Winkler

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    Apr 3, 2013 1:51 PM (in response to voodoo chile)
    Re: Rock found!

    Adam,

     

    It is certainly iron-rich, and there is evidence of crystal structure which hints at iron ore rather than iron itself.

     

    Breaking it open would be useful, but I'll not ask you to do that as it would spoil it somewhat.

     

    First:

    - does it attract a magnet?

    - does it attract a piece of iron/steel other than a magnet?

    - what colour mark do you get when you rub it against the (white, unglazed) back of a glazed tile?

    - and if you fancy determining its density, that could help, too (use water displacement to determine the volume and kitchen scales to determine its mass, then calculate its density as mass/volume in gm/ml)

     

    Mike

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      Apr 8, 2013 3:07 PM (in response to MikeHardman)
      Re: Rock found!

      Density:

      2.7 is basically rock (marcasite would be 4.85-4.9)

       

      Magnetism:

      Repulsion would be unlikely, and considering the low density, no attraction/repulsion is likely.

      Obvously we can rule out iron.

       

      Streak:

      Red-brown could indicate haematite, but it is not dense enough (5.1)

       

      ...Which suggests it is a brown rock.

      The colouration strongly suggests it being iron rich, and I am surprised it is not more dense.

      Its surface structure is a bit difficult to reconcile with sedimentary textures/structures. But also, it does not look particularly of igneous or metamorphic, as a hand specimen. I can't rule out it being of manmade origin (industrial product/waste).

      So the easy tests have not helped much in this case. We'd need to look at it in thin section under a microscope to get an idea of the minerals it is made of.

      You could also try taking it to a local museum; local to where you found it; sometimes such places are aware of artefacts from old industries or curious local rocks.

       

      Sorry not to have been able to give you a decent answer.

      But if you do find out, please post here.

       

      Mike

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    Apr 3, 2013 2:07 PM (in response to voodoo chile)
    Re: Rock found!

    Could it be Marcasite?

     

    [And so castles made of sand slips into the sea, eventually]

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