Vulcanite - a combination of sulphur and India rubber - was developed in the mid 19th century, mostly by Charles Goodyear (the tire guy). It can be white or lots of other colors, plus it's easy to work with, so it was often used to imitate coral, tortoiseshell and jet - especially the latter, as black mourning jewelry became more popular. This Victorian working padlock is fashioned from vulcanite and probably once hung from a necklace made of the same material.