‐-----------------------‐-update 11-11‐----------------------

After more research and some lucky talks I believe this to be epidote from tailings out of the Wolverine Mine, a few miles from where I found these pieces.

‐-----------------------‐-original post------------------------

Was rock hounding on the southern shore of Lake Superior. Found these green crystal deposits that formed like geodes, specimens are small, the largest is about the size of a corn kernel. A local said it could be chlorasolite but I don’t think it matches based on color and clarity. Any thoughts would be appreciated!

  • @Hamartiogonic@sopuli.xyz
    link
    fedilink
    English
    8
    edit-2
    8 months ago

    I have no idea what that is, but it looks beautiful. You should have someone point an XRF gun at it to get a reading of what it’s made of. What if it’s some spicy compound of Cd, Ni or As.

    You could narrow it down with webmineral or mindat, but you might still be left with hundreds of options.

    • YeetPicsOP
      link
      English
      2
      edit-2
      8 months ago

      I’ll check out those resources, thank you! I thought arsenic as well as I know they used to make green dyes from it. Guess I’ll skip the taste-test for now haha

      • @Hamartiogonic@sopuli.xyz
        link
        fedilink
        English
        38 months ago

        People generally think rocks are pretty harmless, but they really shouldn’t.

        Once you know the basics of geology or mineralogy you can look up the metal composition of most of the rocks you find in your environment. After that, there’s no turning back. You’ll never want to lick another random rock again, and you’ll be more cautions about breathing in rock dust.

        • YeetPicsOP
          link
          English
          18 months ago

          This is horrifying and not surprising. I found these pieces on a beach, but noticed they were ubiquitous in almost all the crushed gravel I saw in the town (driveways, fill under roads etc). They seem to have been using copper tailings for all sorts of construction for a long time. I hope it isn’t some nasty concoction, if it is those towns are a fema project waiting to happen.

          • @Hamartiogonic@sopuli.xyz
            link
            fedilink
            English
            18 months ago

            Better send some samples to your local friendly mineralogist. Usually the geological survey of your home country should be able to help. There’s also a good chance these rocks contain boring silicon oxide hydroxide whatever with a little it of calcium and sodium thrown in for color. It’s too early to tell without having them properly analyzed.

  • Hello_there
    link
    fedilink
    48 months ago

    Go shoot an email to your local university geology dept. They might even want you to mail the rocks in.

    • YeetPicsOP
      link
      English
      08 months ago

      They’ll be my next step if I can’t figure it out online easily. Really appreciating the feedback from here though, got a few new resources for this sort of thing, feeling hopeful I’ll get this I’D by sundown.

  • TroyM
    link
    fedilink
    English
    38 months ago

    My gut says chrome diopside, or something in that solid solution. But more than a photo would be required.

    • YeetPicsOP
      link
      English
      18 months ago

      Found it in gravel that likely came from copper tailings if that helps.

      • @Hamartiogonic@sopuli.xyz
        link
        fedilink
        English
        2
        edit-2
        8 months ago

        Copper tailings, you say? It could be a sulfate precipitate of some kind. Probably a mixture of anything and everything, with lots of iron in it. If so, the crystals would be more or less water soluble. If so, you really need to skip the lick test.

        Iron sulfate is usually nice and green, but contaminants tend to alter the color. Also, there are other green sulfate compounds, so narrowing it down without XRF can be tricky.

  • @SatansInteriorDsgnr@lemmy.world
    link
    fedilink
    English
    17 months ago

    This honestly just looks like regular old peridotite in some sort of basaltic groundmass. The crystals would be made of olivine which is very green and the surrounding groundmass I’m not sure, something mafic to ultrmafic though.