A large early Heianjo tsuba.  About 3.2" round.   8.155 cm x 8.124  x  3.92 mm at widest part of the mimi.  My guess is that the web is 2 mm +/-.  There is some old rust damage between 10 and 11 o'clock on the back.   Deep black patina.  Foliage and treeless' in brass and copper hirazogan.  No, I don't think that this is intended to be a Christian tsuba, with secret crosses.  Because of the almost exactly round shape, and thinness of the plate, I think that this is earliest Muromachi.   I suspect that the zogan was added in Momoyama or early Edo, when this was popular.  I think the the kozuka ana is atobori.   Please, do not put too much stock in my opinion.  I once thought that my exwife was a wonderful treasure.  So buy with your eye and knowledge.    $650