I found a lot of obsidian in Oregon State, USA. At one point I got out to see if I could find a sign to get back on track and found that I was crunching along rocks underfoot, covered lightly by pine needles. The sound was familiar so I looked; yup, I was crunching along on a bunch of obsidian. So cool.
At another area we took a rest stop at a place called 'Obsidian Flow' which didn't mean much to us until we stopped and looked at this vast field of rock. It was all obsidian that had flowed downhill with bits of pumice toward the edges. Huge chunks of it were also scattered about. I've never felt so grounded and felt like I could very happily stay there forever.