What is this? A rock that’s odd or some kind of mineral?

I found this at Lake Superior a few years back and can’t find any info on what this actually is, there appears to be some sort of metal which became rusted all around the “rock” but the most interesting ones are being shown in the picture below.

Update:

I used a magnet and all around the entire “Rock” there is Low to Moderate magnetic properties.

Attachment image

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  • 1 month ago

    Has an unusual glasslike quality to it.  The White looks like calcite but the black definitely looks like obsidian, an igneous rock.  Prehistoric man often used obsidian for spear and knife ends as it can be quite sharp when chipped and polished back.

    I have a polished snowflake obsidian rock, inexpensive, but it looks really quite attractive.  Check out one of those also.  

    https://www.etsy.com/au/listing/194601988/one-poun...

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  • 1 month ago

    looks like obsidian to me

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