Vintage Victorian Style Brooch - Silver, Marcasite & Onyx - Beautiful!

This is a unique, classy and beautiful brooch. It measures approximately 2 1/2" long. The black onyx stone is oval in shape - about 1/2" across and about 5/8" long. The rest of the pin/brooch consists of marcasite and silver. Traditional pin clasp. Please review the photos to see the distinctive elegance of this piece. I've worn it a number of times but there are no flaws/issues with the brooch. It has been kept in a covered jewelry case and treated with lots of care. It's a very special piece. Offers welcome & considered.