"But the dilemna of the Valr was this: Arda could only be liberated by a physical battle; but a probable result of such a battle was the irretrievable ruin of Arda. Moreover, the final eradication of Sauron (a a power directing evil) was achievable by the destruction of the Ring. No such eradication of Morgoth was possible, since this required the complete disintegration of the 'matter' of Arda. Sauron's power was not (for example) in gold as such, but in a particular form or shape made of a particular portion of total gold. Morgoth's power was disseminated throughout Gold, if nowhere absolute (for he did not create Gold) it was nowhere absent. (It was this Morgoth-element in matter, indeed, wich was a prerequisite for a such 'magic' and other evils as Sauron practised with it and upon it.)
Ainsi, c'est parce que Morgotha tout corrompu, y compris l'or, même s'il n'a pas créé l'or, que Sauron peut utiliser ce métal, et c'est même un élément déterminant.
Silmo
PS: parmi les autres métaux, il y a le Gavorn, ce métal noir et luisant, dur comme l'acier mais souple et maléable qui constituait l'armure de l'Elfe forgeron Eöl, qui réalisa , Anglachel and Anguirel dans le métal tombé d'un météorite.