Despite what the author claims, I very much doubt if these were minted for paying the rank and file.
It would certain be easier to carry in a paychest than 25 denarii.
> Ariel says soldiers would have to beg the paymaster to change their gold into something spendable.
Roman soldiers who survived their time in service were often rewarded with land, but they were generally paid wine and salt in lieu of part of their pay, and exclusive of billeting and meals.
A great many ancient coin types have survived to the present day; a number of them exist as a single specimen. The coins struck by Aelius Sejanus before he was struck down by order of Tiberius (strangled in his cell,not stabbed as in “I, Claudius”) were restruck or otherwise recycled, such that only about a dozen are known to exist.
The Romans had a better grasp on what money was than many people do today, transitioning into more commonplace bronze coins as the Empire got older and the 50 million or so citizens did more business both with each other and with foreign trade partners. The bronze coins haven’t survived that well in burials, and in very good condition can be quite valuable. On a commodity basis, the gold coins are worth more, but as collectibles not all that much.
The Byzantine gold coins are a little younger and readily available, for those who want to collect. They had a lock on trade between the Black Sea and points n and east, and the Mediterranean and beyond, and their trade reached the British Isles, the Baltic, and until the rise of Islam, India and beyond, so they were hugely rich.
The “widow’s mite” coins, which were struck in copper during the last two centuries BC (and before the Romans conquered the Holy Land) can be found at coin dealers, and they run a great deal more than the value of the copper.