Gold Dust

"Stoke up the magic in the mountain and the Lady will smile. Then watch the swirls that spin so well."

― The clue to the gold dust's source

Gold dust is the substance that allows the Conductor family to travel between Sodor and Shining Time. It is stored in their whistles, which they blow when they want to travel. Once, when the supply was low, Mr. Conductor and Junior had to search for more.