Recently, I was at the conference Shifting Frontiers X, a leading late antiquity conference in North America. At the conference George Benton and Richard Burgess gave an interesting talk on the changing role of gold in late antiquity. Here is an excerpt of the abstract reproduced with permission.
From the time of the introduction of the solidus by Constantine the use and perception of gold were changed radically in the Roman Empire. Silver, hitherto the dominant metal for the making of high-volume coinage, was demoted to use in decoration and gifts, while gold, whether as a unit of account or, increasingly, as bullion minted in solidi, dominated economic exchange. The massive scale of gold use is amply attested in literary sources and papyri, as well as archaeologically in the form of hoards. What remains less clear is whether there was actually more gold circulating… A largely ignored study that used proton activation analysis (PAA) provides tantalizing evidence that a new source of gold became available in the 350s.… This new supply enabled the empire to move to sort of gold standard. With this model in place of the changing use of gold, we are not a position to revisit the earlier trace elementanalyses with new hypotheses. At which minted the gold edge of the empire, was the new goal available in both the East and the West? Where were the mines?
And much of the actual paper was a discussion of which techniques might be feasible for testing coins nondestructively for trace elements like platinum. Best of luck to this project.
For my part, the paper implied that the fall of the Western Empire might be a sort of Grover Norquist scenario, in which all the new extremely high-value money accumulated in the hands of the ultra-rich, and the Imperial government became small enough to be drowned in a bathtub.