Found a chunk of what I thought was obsidian in a creek bed near Bend

I mean, it was black and glassy, so I was sure. Took it to a local rock club meeting and a guy pointed out the conchoidal fractures were way too big and grainy. It was actually slag glass from an old smelting operation, which makes sense given the area's history. He showed me under a 10x loupe and the tiny bubbles were a dead giveaway. Anyone else run into industrial slag masquerading as cool volcanic rock?

2 comments

2 Comments

anthonyy553h ago

I've got a whole box of "maybe obsidian" that's just old bottle glass from an old dump site on my property. The bubbles get me every single time. I felt like a real expert until I actually found a real piece.

brookebailey2h ago

Honestly, I kind of like the slag better sometimes. It has its own story, you know? That glass was part of some old factory or railroad work, people making a living. It's still a piece of the area's past, just not a natural one. Finding it is its own kind of cool history lesson, even if it's not a volcano rock.