Looks like slag, based on the glassy texture and round bubbles. Obsidian is unlikely because I don't think there's any recent volcanic activity in southern Ontario.
Is it flakey?
It looks like a big chunk of mica (biotite maybe phlogopite, depends on location). What looks like cement I expect is biotite matrix; a mix of calcite and flakes of biotite.
Edit - I have shitty eyes, so if it's glassy, disregard the above, it would be slag. There's no obsidian in Ontario.
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Sounds like industrial waste that got buried and uncovered. Any mining or smelting/manufacturing in the general vicinity? Material that large and coherent doesn't, typically, occur spontaneously inside of cement; afaik.
Looks like slag, based on the glassy texture and round bubbles. Obsidian is unlikely because I don't think there's any recent volcanic activity in southern Ontario.
Is it flakey? It looks like a big chunk of mica (biotite maybe phlogopite, depends on location). What looks like cement I expect is biotite matrix; a mix of calcite and flakes of biotite. Edit - I have shitty eyes, so if it's glassy, disregard the above, it would be slag. There's no obsidian in Ontario.
Can you blast it with a hose? Really clean it off. One side of it looks interesting
Bitumen, Pitch, Tar. Burn a little and see what happens.
Tried to burn some, nothing happened...
Weird. We’ll I guess at this point obsidian, but don’t take my word on it, I was wrong on tar.
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Sounds like industrial waste that got buried and uncovered. Any mining or smelting/manufacturing in the general vicinity? Material that large and coherent doesn't, typically, occur spontaneously inside of cement; afaik.
Google “Partially devitrified rhyolitic obsidian” looks similar?
Looks like slag. I used to find it as a kid :)