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c/geology-rocks•mason_knightmason_knight•2mo ago

Can we talk about people calling every shiny black rock obsidian?

I was at a rock swap in Tucson last weekend and saw at least five different tables selling slag glass as 'rare volcanic obsidian' for $20 a piece. It matters because new collectors are getting ripped off and it muddies the real market. How do you even start to explain conchoidal fracture to someone who just got burned?
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3 Comments
jana_henderson52
It's like that with fancy olive oil now too.
6
paige514
paige5141mo ago
What if the fancy bottles are just to hide bad oil?
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henry_webb68
Slag glass usually has bubbles inside, real obsidian doesn't.
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