Sterling Silver Marcasite and Amethyst? Drop Pin Brooch

Sterling Silver Pin Brooch with Marcasites and what looks like Amethyst Gemstone. Marked 925 for Sterling. I don't know for sure if the stone is Amethyst, but the pin is sterling, marked on back and is covered in Marcasites with the stone dangling below, so please see pics. Closet clean-out week! I'm selling a lot of jewelry and clothes, so please check out my closet. Bundle up for discounts, make me an offer! Thanks for looking!