Mack/Sophist and Malcolm Douglas, you have answered my query pretty well. And thank you. And thanks to others who gave information, too.

Peregrina said:

I think it's a poetic epithet; it's unlikely to be a specific alloy in that poem--or anyway, it can't be verified because it's a work of fiction.

Actually, the Nibelungenlied is not quite a work of fiction. Or maybe I should say "not thoroughly a work of fiction". It's a poetic fictionalized and extended version of historical facts and situations, composed about six or seven hundred years after the facts portrayed, based on several earlier preexisting heroic lays on the same events. After the standards of the time, it was not only entertainment but a presentation of history. Of course it's true that it's dressed up with prophecies and a few mythical creatures, like nixies (water sprites), and a brief passing reference to a dragon, but King Etzel is the historical Attila the Hun, and Siegfried (aka Sigurd, Sifrit, et al.) was actual, and Brunhild (aka Brunhilda, Brynhilt, et al.) and Kriemhild (aka Gudrun, Grimhilda, Grimmhilt, Grimmelda et al.) and many more characters are historical, as are the high-level marriages of Kriemhild to Siegfried and (some years after Siegfried's murder) later to King Etzel, and the marriage of King Gunnar of Burgundy to Brunhild, and the betrayal and battle which wiped out the King, court, and army of Burgundy ("the Rhenish lands") are poetically dressed-up history.

But Peregrina is correct that, as a work of heroic poetry (a sort of historical novel of its time, I suppose you might say), the Nibelungenlied is not checkable as to details of expression after about fifteen centuries from the original facts and eight centuries after its composition by an anonymous minstrel.

But the expression "red gold" for treasure objects and coinage is not restricted to that work, nor to those particular times and areas, and I wanted to know if the expression "red gold" held more than a mere romantic or poetic reference to "gold" gold. From what several here have said, I conclude that it was intended as fairly straightforward   description of the metal objects involved.

Dave Oesterreich