It is an eruptive rock of a volcano. Ebonite. Rubber black and very hard.
Vulcanite: Telluride Yes, ple of copper, which crystallizes in the Orthorhombic system and dipiramidal.
Group of eruptive rocks thrown by a volcano.Vulcanized rubber black and very hard, can be carved and polished: the vulcanita is used to make Electrical insulators.