A strange specimen! This is a complete schorl, floating and doubly-terminated, complete and undamaged. But, millions of years ago probably, it separated and then rehealed even as it was forming leaving a slight disjunction at that point, resulting in the few millimeter sharp offset you see here. It LOOKS like the piece will slide apart like a few cards coming off a deck, but its on there, cemented back together in situ, and certainly at the same time it was even forming. Doubly-terminated.