Ebonite is one of the earliest forms of plastic. A hard, rigid and shiny resin, it was intended as an artificial substitute for ebony wood.
It is actually a very hard rubber first obtained by Charles Goodyear by vulcanizing rubber for prolonged periods.
As a result, it is about 30% to 40% sulfur. It is often used in bowling balls, smoking pipe mouthpieces,
fountain pen nib feeds, and high-quality saxophone and clarinet mouthpieces.
It is alo commonly used in physics classrooms to demonstrate static electricity.
(source: wikipedia.com)

[0388 x2] Two small ebonite dice, 10 mm