Early
phenolformaldehyde-based
plastic invented by Leo H. Baekeland in
1907 - the first completely
synthetic resin.
Popular due to its versatility and many applications, bakelite quickly gained status as a household material since it replaced other, more expensive materials as ebony for billiard balls and ceramics or glass used in electrical insulators.
Older telephones are often made out of bakelite and considered de rigeur in any steampunk setting.