This is a dramatic mod vintage large sterling silver atomic style abstract moss agate brooch. It is unmarked. The setting tests positive for silver content of sterling grade. The design features flat solid ovals of silver alternating with open oval loops, and a single large oval agate cabochon stone in the center. The back has a standard pin back with functional roll over safety clasp.
This brooch weighs an impressive 45.9 gr. It measures approximately 3" x 3". The center stone measures 1" x 1.625".
Condition is good, with minor expected surface wear to the silver.
Add a silver bail loop and this piece could also be worn as a pendant. I estimate that it dates from circa 1970s.