Adamantine Weapon?

[Pope Scarface]

Are there rules for adamantine weapons in 5E, or other special materials?

[RickAllison]

Are there rules for adamantine weapons in 5E, or other special materials?

I know that they do distinguish them in one way, namely that some creatures can be harmed by nonmagical adamantine weapons rather than silvered. However they never go into how to get them by my figures.