I found this fragment earlier this year and puzzled over it for a long time. The site is almost exclusively 1770's to 1820's.
After looking at HEAVYMETALNUT's Luckenbooth Brooch, I'm wondering if this could be a fragment of something similar.
Thanks, Matt. I'll investigate that possibility. Scrolling back and forth, I can't visualize how the little hinge would work in the buckle design, but I'll cut and paste a side-by-side, so I can see it better.