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OT - Metal? Mysterium? Cannonball?

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  • boslab
    replied
    I havent a clue what it is but what i'm looking at is the distinct presence of solidification patterns, it was liquid, and cooled from the outside inward, the dendritic aka columnar features always follow the directiom of the temperature gradient, cooling was very fast, more than 50% of the shell is dendritic, this formed the crust,in the central portion the remainder of the mass seems to show that cooling was slower and equiaxed crystals have formed.
    the 'rays' are inward not outward, judging by this a water quench was involved,like ingot casting

    mark

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  • laddy
    replied
    Petrified dianosaur turd!!!!!

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  • Weekend_Scientist
    replied
    Magnets

    On the issue of "does it stick to a magnet"

    Do you want to know if something interacts with a magnet, even very weakly? Try this:

    Get about a one inch diameter neodymium iron boron magnet and suspend it from a piece of thread. If possible, the thread should be a foot or more long. Mount the thread to a fixed object like a shelf over your workbench. This will give you something of a pendulum with the magnet as the bob and very little force will be needed to deflect the magnet.

    Then bring the object under test near the magnet. If the mystery object even weakly interacts with the magnet it will noticeably deflect the magnet.

    If the magnet doesn't settle down fast enough for your liking, put a large aluminum or copper plate below but not touching the magnet. This will dampen the swinging (eddy current breaking) but will not attenuate the interaction of the magnet with the mystery object.

    Obvious disclaimer: Don't bring a large iron object near your "magnetic pendulum" You will instantly break the thread as the magnet goes screaming toward the iron. You'll probably end up breaking the magnet too.

    --Weekend

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  • daryl bane
    replied
    We, as kids would find them in soft shale in creek beds. We erroneously called them, "fools gold". If you break it open, it is quite pretty inside.

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  • Weekend_Scientist
    replied
    Was pyrite, is now hematite/goethite

    BobL is spot on with his description:

    "" . . a weathered pyrite (or marcasite) nodule. The mineral was originally iron disulphide.
    I can tell from the way the original crystals radiate out from the center of the nodule (right hand image)."

    I pick these things up around Austin, TX from time to time. The ones I have collected are definitely pyrite (as opposed to marcasite) confirmed by powder x-ray diffraction. The nodules typically have a granular center and then crystals radiating outward. They originally formed under low-oxygen conditions. Once exposed on the surface, the pyrite (iron sulfide) turns into either hematite (iron oxide) or goethite (iron oxide-hydroxide) or limonite (iron oxide hydroxide hydrate).

    We home shop machinists should know goethite when we see it--it is naturally occurring rust :-)

    --Weekend

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  • john11668
    replied
    Originally posted by MickeyD
    That looks a lot like a chunk of river tumbled low grade iron ore. We had a lot at the farm when I was growing up and smaller chunks were great in slingshots.
    I would agree with Mickey
    Haematite (kidney ore) exhibits that crystalline appearance

    The fractured back of this sample would exhibit the crystalline structure you see. I think your sample is just heavily corroded

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  • dian
    replied
    "2. Heavy, like Lead or dense Cast Iron."

    what is dense cast iron?

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  • Tim in D
    replied
    Bobl has it right. It's a pyrite nodule common in Tx. They form in the limestone that is the underneath most of the state. Before we were a Republic ,we were an inland sea!

    Tim in D

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  • BobL
    replied
    Originally posted by CCWKen
    It might be a silicon carbide meteorite. If so, it could be very rare. It may be what is left of a star that went super-nova. These typically have other rare metals in granular state too. Don't let it out of your sight.
    Many meteorites contain micron size silicon carbide grains and nanometre size diamond grains (I have studied these so I know a bit about them) but a solid SiC meteorite would indeed be unusual beast as none have been found yet.
    Last edited by BobL; 07-11-2012, 02:43 AM.

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  • CCWKen
    replied
    It might be a silicon carbide meteorite. If so, it could be very rare. It may be what is left of a star that went super-nova. These typically have other rare metals in granular state too. Don't let it out of your sight.

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  • dp
    replied
    If it's terrestrial in origin it seems reasonable to think that field will have a lot more. An hour with a metal locator would reveal that.

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  • BobL
    replied
    And the verdict is . . . . .

    According to the Curator of Minerals and Meteoritics (Dr Alex Bevan) at the Perth Museum it's;

    " . . a weathered pyrite (or marcasite) nodule. The mineral was originally iron disulphide.
    I can tell from the way the original crystals radiate out from the centre of the nodule (right hand image).

    Can't really tell if the original pyrite has been completely altered to iron oxides or oxyhydroxides of iron.

    Such nodules often form in a variety of sedimentary rocks by the percolation of iron and sulphur rich fluids. The origin of the sulphur is from decaying organic matter and the crystals grow outwards from a nucleus.

    Because they are harder than the host rock, they often survive after it has completely erode away. So the nodules come to lie on apparently unrelated surfaces and appear exotic."

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  • KiddZimaHater
    replied
    I think MickeyD is right.
    I did a little research, and tried the ceramic streak test.
    I think my daughter has discovered HEMATITE.

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  • BobL
    replied
    Originally posted by Mike Burdick
    Here's why it's probably not a meteorite...

    http://www.aerolite.org/found-a-meteorite.htm
    That site is not that cluey about meteorites.
    This is a quote from their site.
    "Please remember, a meteorite will stick easily to a good magnet. If your rock does not adhere to a powerful magnet you almost certainly do not have a meteorite. There are many Earth rocks that also stick to magnets, so if your specimen adheres to a magnet it is not automatically a meteorite, but it's a step in the right direction"

    This is incorrect. Stony (non-magnetic) meteorite finds outnumber iron meteorites finds by a looooong way. A representative ratio of irons to non irons can be found by looking at the NAS antarctic meteorite collection . As of a couple of years ago they had ~16,000 meteorites of which only 107 were irons.

    BTW I have forwarded the pictures for comment to a friend of mine who is the Curator of Meteorites at the Perth Museum.

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  • MickeyD
    replied
    That looks a lot like a chunk of river tumbled low grade iron ore. We had a lot at the farm when I was growing up and smaller chunks were great in slingshots.

    Leave a comment:

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