Vintage Sterling Silver Mayan Calendar Brooch Pendant

Sterling silver Maya calendar brooch/pendant is marked Hecho En Mexico 925 and an eagle mark.  It features a large spiral diamond cut border and a hidden 4mm bail.  The eagle mark tells that it was artisan made sometime between 1948 - 1970's.  It has a diameter of 1 1/2 inches, and it weighs 12.5 grams.  It is in great condition.