Original: In The Lord of the Rings , Tolkien writes that mithril was found only in Khazad-d ûm ( Moria ) in Middle-earth , where it was mined by the Dwarves .
Simplified: It was only found in Khazad-d ûm ( Moria ) , where it was mined by the Dwarves , and ( perhaps ) in Númenor .