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Differentiating Natural Versus Man-made Holes In Stone

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  • Differentiating Natural Versus Man-made Holes In Stone

    Hi all,

    It's been a while since I've posted. Maybe more on that later.

    A friend recently brought me a small stone that she found on a local (Massachusetts) beach that has a small hole through it. I believe it is a "hag stone" and that the hole was created by a Piddock, snail or erosion. The stone is suspiciously shell-shaped but fossils are extremely rare in Massachusetts due to glaciers pulverizing most of them during the last ice age. Whatever it is, it's a cool find for sure... but I do not believe it is a man-made artifact. But that got me thinking...

    How would one differentiate between a hole created by natural means (i.e. a piddock or erosion) and one that was drilled by an ancient human?

    The first set of photos (the ones who's titles start with "AJ") is of the small stone my friend found. Natural, right? Note: In the last photo the red arrow points to an indentation that looks like it is in line with the hole that runs through the rock.

    The second set photos (in the post below and who's titles start with "CH") is of a supposed "artifact" that comes from an old collection from Ipswich, MA that the finder (now long-since deceased) had labeled as a pedant. For context, Ipswich does boarder the ocean, however I do not know if the "pendant" was found on a beach, river or one of the plowed fields that the majority of his collection was found.

    Are there any tell-tale characteristics that would indicate if either of these two holes are natural or not?

    Thank you in advance for your input.
    Attached Files
    Last edited by Atlantic City; 09-27-2022, 09:15 PM.

  • #2
    "Pendant"
    Attached Files

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    • wooddoug
      wooddoug commented
      Editing a comment
      I'm not a hole expert but here's what I think I've learned over the years. As far as holes through thin material like this, most of my examples are biconically drilled, but a few are conically drilled.
      Long holes through banner stones that are made from hard stone are core drilled and kinda biconically drilled, since they gradually taper just a little toward the middle. Any time I see a perfect diameter straight clean hole like on your example I assume natural or drilled with a steel bit by modern man. My last bit of "hole lore" learned from an even oldertimer than myself is about pipe holes. A hole in a genuine hard stone pipe will be core drilled but will either have a nipple at the bottom of the bowl where the core was, or will show where that nipple has been chipped off. If it comes to a smooth rounded or conical bottom run away.

  • #3
    I am far from being an expert on geological phenomenon so take my opinion for what it's worth (not much) but my WAG is that all are natural stones.

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    • #4
      They look natures work to me also.

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      • #5
        They look natural. Especially in the case of the second example, one expects a selection of material based on attractiveness. From that standard, the second one fails, it would be odd to select such an unattractive stone.
        Rhode Island

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        • #6
          Thank you for your input.

          I think I am going to downgrade the "Pendant" from "Artifact" to "Geofact". I guess since the original collector had called it an artifact I just went along with that. There's one or two other items in his collection I am not sure of now also. They too might get moved into the "maybe" box.

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          • #7
            Most anciently drilled stone artifacts are biconically drilled from both sides. The hole is generally smaller in the middle of the stone. Some of my favorite artifacts with good examples of ancient drilled holes:

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            Michigan Yooper
            If You Don’t Stand for Something, You’ll Fall for Anything

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            • #8
              Any prehistoric drilled hole will be cone shaped on o ne or both sides.
              FGH

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              • Ron Kelley
                Ron Kelley commented
                Editing a comment
                Most will be cone shaped but I have seen some reed drilled holes that were cylindrical.

            • #9
              Ron is right reed drilled is a real technology. I have found things like your friend, all natural. For instance People around here found Crinoid stem pieces and always thought they were Indian beads. K
              Knowledge is about how and where to find more Knowledge. Snyder County Pa.

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              • Ron Kelley
                Ron Kelley commented
                Editing a comment
                Hey Kim, You're right the crinoid stems are not man made of course. Ancient people did collect them. I have several hundred that were found on an ancient Texas site. There were enough to make five 30 inch strands.
                Last edited by Ron Kelley; 10-22-2022, 02:28 AM.

            • #10
              These natural crinoid stems were found on an ancient site in Texas:

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              Michigan Yooper
              If You Don’t Stand for Something, You’ll Fall for Anything

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              • Mattern
                Mattern commented
                Editing a comment
                I know that they were used Ron. I never heard of a cache found around here. just single finds in fossil areas. K

            • #11
              If the rock has conical sides on both sides of the hole it may have been drilled by prehistoric people. If not, it wasn't drilled by them.
              That doesn't mean it wasn't found and used as is. It just means they didn't drill it.
              FGH

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