** LOTR - Moria

Right between the shadow of the trees there was a smooth space, and over this [Gandalf] passed his hands to and fro, muttering words under his breath. Then he stepped back.
'Look!' he said. "Can you see anything now?'
The Moon now shone upon the grey face of the rock; but they could see nothing else for awhile. Then slowly on the surface, where the wizard's hands had passed, faint lines appeared, like slender veins of silver running in the stone. At first they were no more than pale gossamer threads, so fine that they only twinkled fitfully where the Moon caught them, but steadily they grew broader and clearer, until their design could be guessed. --FotR, "A Journey in the Dark"