Unfortunately I no longer have that chunk of obsidian. And I don't remember where we were in Vermont. I found it when I was about 6 years old and kept it for several years but eventually lost it (along with other childhood treasures, like a big bag full of fossilized sharks teeth I had collected over the years).
The obsidian chunk was a little bit larger than a softball and completely black except for some other bits of cement-like material stuck to parts of it.
I was always finding cool stuff when I was a kid. Here's another one I never figured out...
A completely spherical rock that I found in my driveway. It was smaller than a golf ball, but larger than a marble. It was un-naturally spherical (perfect as far as I could tell), but it wasn't made out of glass (otherwise I would have thought it was just a worn marble). The stone material was a slightly reddish color with a small worn crack running through it. I imagined that it was an "Indian Marble" (a rock worked into a sphere by some ancient culture), but I never knew for sure, and I don't even know if indians ever made such things.
I found the rock in my driveway which was piles of rocks which probably came from a quarry which sold broken material like that for developments, so there's no telling where that spherical rock actually originated. It could have come from the mid-west in a shipment of gravel or something.