Mithral, also spelled mithril and known as truemetal among the Dwarves, is a silver-white metal that is considered to be stronger than steel and half as light.
Since pieces of armor made from this valuable metal were very light, they allowed the wearer to make better use of their natural agility and were less restrictive on spellcasting.
Despite its steel-like properties, it was polished like silver and never tarnished.