I believe this is a pretty rare type, since I don't recall ever seeing another quite like it. Color is on the greenish side of aqua and it contains some ribbons of graphite. Any info is appreciated. The triangular recessed base is quite unusual. The glass and manufacturing process gives the impression of a circa mid 1800s item. (The pic shows a side view and base view of the same piece.)

Update: It appears there are at least a half dozen or so of these known.