Pretty artifact !
If obsidian was all they had to use, if there's a high-angled edge on it, it probably was, or could have been. But obsidian is a last-choice material for scraping tools because it's so brittle. When they could find glacial cobbles of chert, even though they had to search long and hard for them, they cracked these and made scrapers of them : they held an edge.
Looks like it was a knife (low-angled edges), FWIW.