Mithril

Mithril is a lightweight metal utilized by dwarves and elves to produce armor. Its properties are analagous to silver, but it will not cause silver damage if wielded.

A mithril-coat is a valuable possession in the early and mid-game. Dwarvish mithril is slightly better than elven mithril when not enchanted (AC 6 versus AC 5) but like all elven armor, elven mithril can be enchanted to +7 while dwarvish mithril is limited to the standard +5. Mithril is usually abandoned for dragon scale mail before the end game, so players are often reluctant to enchant mithril and usually prefer dwarvish if a choice is available.

A mithril coat will hinder spellcasting, although it is light enough for magic users to carry around just in case.