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I think this river stone is basalt, but my buddy insists it's slate.

From my look, the feel points to basalt, but he says the lines show slate. We're stuck, and I'd like to hear other thoughts. What do you all say?
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4 Comments
the_dylan
the_dylan1mo ago
The fine lines on that stone show slate's cleavage. Basalt is often solid without those layers. Trust your buddy on this one.
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eric_gonzalez26
Oh man, I totally did this last year. I had a pile of flagstone and swore it was basalt. A buddy made me do the scratch test with a nail, and slate flaked right off. That hardness check is a solid way to tell, in my experience.
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faith_lopez
Yeah, those fine lines are a dead giveaway for slate. My friend was so sure her patio stones were basalt until she tried the nail test. She pressed a nail into one, and it flaked apart in layers, just like you said, @the_dylan. Now she double-checks every stone before buying.
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taylor.jessica
Wait, the nail test made it flake apart? That's wild, @the_dylan wasn't kidding about slate.
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