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Armenian Blue on Orange Obsidian

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  • Armenian Blue on Orange Obsidian

    I am curious to learn how this Obsidian was created. I have seen lots of obsidian with different colors in it but nothing else with this odd separation of colors. I have notice that on all my slabs there is a dark border on the blue spots. I suspect that there is something in the blue rock that prevents it from easily mixing with the other rock. The Obsidian comes from the mountains of Armenia.

    Click image for larger version  Name:	12.jpg Views:	1 Size:	65.8 KB ID:	395358 Click image for larger version  Name:	14.jpg Views:	1 Size:	60.8 KB ID:	395359 Click image for larger version  Name:	11.jpg Views:	1 Size:	60.9 KB ID:	395360
    Michigan Yooper
    If You Don’t Stand for Something, You’ll Fall for Anything

  • #2
    Or maybe it’s the flip side Ron . Maybe the blue mineral was cooled last , forming the boarders .
    Thats an entire research team .. it beautiful .
    Mother nature at its best .
    now darn it I have to look this up .

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    • #3
      Looks like street cobbles in a way. That is arguably the coolest looking Obsidian on the planet. Just my opinion.
      "The education of a man is never completed until he dies." Robert E. Lee

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      • #4
        That’s some fabulous material Ron. This may help your understanding.

        Obsidian forms from felsic lavas that cool sufficiently quickly that they don’t crystallise (although they often contain variable amounts of crystalline impurities). That’s why it has an amorphic glassy structure. If that same lava had cooled more slowly then it would usually have become a felsic rock such as a rhyolite or a granite.

        It’s that same rapid cooling which creates the ability for obsidian to have a marbled appearance. If you have two (or more) lava outflows with the composition required to create obsidian, but with different colourations by virtue of impurities then they only have a limited amount of time for any co-mingling before they solidify together and capture that pattern forever. The degree and nature of any co-mingling is also influenced by differences in viscosity between the molten streams, minor variations in melting point, the violence with which the magma was ejected, and the degree to which escaping steam or expanding air bubbles ‘stir the pot’.

        Banded or striped patterns usually arise from slow laminar flow of molten lava where the outpourings then cool in sequence (top to bottom or vice versa, or edges to middle), or where it has created alignment of mineral impurities in the direction of flow. The mineral hedenbergite notably creates these kinds of striped patterns in laminar flows. Marbled patterns like yours are usually associated with more violent expulsions of magma in spurts or large eruptions. Spotted patterns (such as snowflake obsidian) usually arise long after the obsidian has solidified by chemical alteration during hydration, with crystalline impurities acting as the nucleus for change.

        The dark border you can see is likely the result of limited chemical interaction of impurities at the boundary before solidification and may well have been accentuated over time by hydration.
        I keep six honest serving-men (they taught me all I knew); Their names are What and Why and When and How and Where and Who.

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        • Ron Kelley
          Ron Kelley commented
          Editing a comment
          Thanks Roger, That sure does help me better understand this unique obsidian.

        • beatup1354
          beatup1354 commented
          Editing a comment
          Great explanation of the cooling process .

      • #5
        Ron... my response was 'shoot from the hip' about obsidian in general and I 've now looked more closely at the specific material you've shown. I would be pretty certain that this has been formed from two or more successive eruptions of magma. The blue material was from the first eruption and solidified first, perhaps forming a sheet or crust over the fissure from which it came and/or the general surrounding area. It has then been broken into fragments of various sizes by a subsequent eruption(s) of the orange material, which carried it as fractured debris until it too solidified. It's the pronounced angularity of much of the blue material that leads me to that conclusion. They're effectively clasts, in what might be more properly called a volcanic breccia, but with both the clasts and the cementing matrix composed of obsidian.
        Last edited by painshill; 10-05-2019, 10:57 AM.
        I keep six honest serving-men (they taught me all I knew); Their names are What and Why and When and How and Where and Who.

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        • Ron Kelley
          Ron Kelley commented
          Editing a comment
          WoW, Thanks Roger, That is a great explanation of what happened here. I had commented in an earlier knapping thread that it looked like blue shards were dumped into the molten orange rock. With your detailed explanation I now understand why this pattern of obsidian is rather special or rare.

        • beatup1354
          beatup1354 commented
          Editing a comment
          Great bit of detail on how thus material may have formed in my own mind i thought it looks a lot like some brecciated jaspers

      • #6
        Kinda looks like Eastern European obsidian but not combined the same or cut at a different angle .
        SE IA

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        • Ron Kelley
          Ron Kelley commented
          Editing a comment
          You're right it is.

      • #7
        That's takes the Cake on wild color combos in my book! Never knew something like that existed. Can't wait to see this stuff knapped...
        ​​​​​
        Josh (Ky/Tn collector)

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        • Ron Kelley
          Ron Kelley commented
          Editing a comment
          Hey Josh, Bret and I have knapped a few blades already. I bought several slabs of this rock because it's so different from what I usually see.

        • Kyflintguy
          Kyflintguy commented
          Editing a comment
          I'll look and see if I can find it. Agreed it's different I couldn't have passed it up either.
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