It appears that vulcanite is a term currently used for a copper telluride mineral discovered in 1961 in Vulcan, Colorado. Previously it was a "generic" term for very hard, vulcanized natural rubber, that was trade-named Ebonite. The vulcanization process was discovered by Charles Goodyear, and refers to adding sulphur to natural rubber to crosslink the polyisoprene and other molecules in the chemical "soup" that is natural rubber latex (tree sap of the New World Hevea tree). Goodyear did not coin the term "vulcanization" for his process and appears he did not use vulcanite as a term to describe his materials.

I don't know what material was used for the thin disk beads that are strung on raffia, generically called vulcanite by bead people, and are part of the "African trade". If I have time at work I'll see if I can determine what polymer the disks are made of, because now I'm curious.

I've never seen the term vulcanization or the name vulcanite capitalized, probably since neither term was ever trademarked, to my knowledge.