Darklands Puzzle #14

Your way is blocked by an iron door. Carved above it are the words:
ALL FACES SPEAK TRUTH.
THE FACES ARE NAMED NARM, NENN, AND KROCHT.
THEIR FATHERS ARE HOD, ELT, AND MOT.
TOUCH KROCHT TO OPEN THE DOOR.
On the door are three metal faces: gold, silver, copper. They speak:
Gold: "Narm is not silver. The son of Hod is copper."
Silver: "Nenn is not gold. The son of Elt is Krocht."
Copper: "The son of Mot is silver."
Which is Krocht? The order of names and fathers is clearly irrelevant. You touch...
...the gold face.
...the silver face.
...the copper face.

(Source: Darklands cluebook by MicroProse Software)

The key here is to ignore irrelevant details and focus on the following two statements: "the son of Hod is copper" and "the son of Mot is silver". There is only one metal left for the son of Elt (i.e. Krocht): gold.