This Mid Century Mexican folk art silvertone artisan brooch depicts a stylized indigenous folk art fishermen motif with five dangling fish below the boat. I found two others just like this online, attributed to Jesus Cazares in the Patzcuaro region, and pictured in the Davis & Pack Mexican Jewelry book. This artist's jewelry appears in at least one folk art museum.

Both of the online pins I saw are unmarked, but based on when and where it was made, it's highly likely to be sterling silver. The pin measures 2-1/4 by 3-1/4 inches and weighs 35 grams, another indication it's sterling rather than Alpaca or another light weight metal. The back has a lot of tooling and planishing marks, making it hard to read any intentional markings. I've darkened and enhanced the last picture in order to better show a mark that appears to be lettering just above the middle fish. It could read Mexico, or something else. The second photo is much more accurate as to coloring and condition that the last, altered picture.