Antique book chain, silver-toned links and gold-toned beads. It has an intricate, articulated design which was popular in the Victorian era. 
The primary structure appears to be a silver-toned metal, likely sterling silver or plated metal, while small spherical beads adorning each link have a gold tone. 
The necklace is a choker or collar length, designed to sit high on the neckline. Measures 44cm long.