skp and I went for a hike today in Annadel State Park. The trail (Steve's S) was littered with obsidian. It's a shiny black volcanic rock that feels like glass – only harder. The Pomo Indians used to gather obsidian from the area to make arrowheads. At one point, we stopped on the trail to pick them up to study them. It was fun. It's great to be enthusiastic about rocks. I remembered that I used to have fun with rocks as a kid. When did I stop?