Circa 1960s-1970s. Made in Mexico.
Back of brooch is stamped "925", "TAXCO", "MEXICO", has eagle hallmark with a "3" inside, and appears to have an artist mark of "NB".

The eagle marks were instituted by the Mexican government in 1948, and the number on the eagle's chest represents either the city of assay or an individual maker (#3 represents Taxco).
Circa 1979, the eagle system was put to rest and replaced by a new letter/number mark to indicate the silversmith and guarantee sterling standard.

A highly detailed Aztec (Mexica) calendar design inspired by the iconic Sun Stone. The brooch showcases a bold central solar face surrounded by concentric rings of symbolic glyphs and geometric motifs, all rendered in deep relief. The central face with the protruding tongue is the solar deity Tonatiuh, a hallmark of the Aztec Sun Stone.

Can be worn as a brooch or pendant!
Brooch has a diameter of approximately 1.5 inches.
Weighs approximately 14.25 grams.

In good condition with no noticeable flaws. May have some minor patina as expected with age & wear, but can be polished if you desire. Please see all photos.