This is a quirky American Arts and Crafts brooch of brass and faux verdigris, dating to about 1915. It has a simple acid-etched abstract design and appears to have been gilded with a brighter metal, followed by an application of faux verdigris. The whole has then been rubbed down to achieve a “distressed” or rustic appearance.
Overall, it is very similar to the simplest Forest Craft Guild brooches, often finished with an “antiqued forest green” – and often considered too basic – but it is not signed. It is fitted with a simple c-clasp.
6 cm wide by 4 cm high (2.4″ by 1.6″).
The style of the brooch makes it deliberately “flawed” but I would say it is in close to original condition, which most likely included the mottling and discolouration visible on the back.