Vintage 1960s chunky spiral necklace, Mexico Sterling silver hypnotic pendant

A very 1960s Italian style spiral pendant - or perhaps more of a Twilight zone twist? Get ready to be hypnotized by this beauty! In a chunky style, the pendant is quite thick, but not too heavy.....it could be hollow. The black area on the spiral looks to be a stone and could be onyx. The large hanging loop makes it easy for a multitude of chains to pass through. It is marked " Mexico 925" on the back. It comes with a flat linked chain (unmarked) on which all the little rings and connections have been soldered shut - a great mark of quality. In good shape with minor signs of age and use. Size: Pendant diameter 40mm, 7 mm thick Chain length 19.5 inches (50 cm)