Where have our Eagles gone?

[Forty-One]

I am opperating without source material on hand, but I could have sworn that I read that Marius was responsible for the introduction of a "gilded" eagle, suggesting of course that the gold was only a surface layer - but applied over what would be a good question...

The source is Pliny's Naturalis Historia . He mentions nothing about the colour or material:

[Plin. Nat. 10.5] "Romanis eam legionibus gaius marius in secundo consulatu suo proprie dicavit. erat et antea prima cum quattuor aliis: lupi, minotauri, equi aprique singulos ordines anteibant. paucis ante
annis sola in aciem portari coepta erat, reliqua in castris relinquebantur; marius in totum ea abdicavit."

("Caius Marius, in his second consulship, assigned the eagle exclusively to the Roman legions. Before that period it had only held the first rank, there being four others as well, the wolf, the minotaur, the horse, and the wild boar, each of which preceded a single division. Some few years before his time it had begun to be the custom to carry the eagle only into battle, the other standards being left behind in camp; Marius, however, abolished the rest of them entirely.")

Could someone please post evidence for golden eagle standards? I haven't found any so far.