I found, what appears to be, obsidian on a hike in SE Wisconsin yesterday. The problem is that I know obsidian isn’t part of the geological makeup of SE Wisconsin. Am I wrong that it’s obsidian or can it be glacial till? Or was it dropped by a Native American sometime in the past?

I found, what appears to be, obsidian on a hike in SE Wisconsin yesterday. The problem is that I know obsidian isn’t part of the geological makeup of SE Wisconsin. Am I wrong that it’s obsidian or can it be glacial till? Or was it dropped by a Native American sometime in the past?