For your consideration is this nice and very well made marcasite pin. It was nice well cut triangular slabs of mother of pearl, carnelian, chrysophase and either jet or onyx. What a great aesthetic and a nice thick sturdy brooch. Marked 925 on the back center. Circa 1980s I believe....possibly earlier.
The pin measures 1 and 7/8 inches by a hair under 1 and 1/4 inch.
It is in excellent functioning condition with no damage. The sterling has a nice patina.