"That spear-thrust would have skewered a wild boar!"—Aragorn, after seeing that the coat had blocked a spear wielded by a Cave Troll, in Moria
"Mithril! All folk desired it. It could be beaten like copper, and polished like glass; and the Dwarves could make of it a metal, light and yet harder than tempered steel. Its beauty was like to that of common silver, but the beauty of Mithril did not tarnish or grow dim." (The Fellowship of the Ring, "A Journey in the Dark").
No Troll, Orc, Zombie or Creeper can pass through!