Genuine Marcasite Butterfly Necklace

Genuine Marcasite Butterfly Necklace. 18inch chain with Butterfly Marcasite Pendant. Quite unique chain...see pics. Size of pendant in pics. In like new condition. Zero flaws. Not sure which store this came from, has been stored in silver safe jewelry box for years. No markings on necklace. Not sure if sterling. (Thinking it would be marked if was). Pet friendly home