I purchased a lot of shipwreck coins found by diver/fishermen off the coast of Java back in ~ 1965.
The "trove" consisted of a mixture of copper and bronze coins of both Oriental and Dutch origin. Many of the coins were 1 and 2 "duit" Dutch coins bearing the Dutch East India logo ("VOC") on obverse and the denomination and date on the reverse. Most coins were dated 1790 although there were a few 1824s and an 1834.
The Oriental coins i.e., the generic Chinese "cash" design coins with the square in the middle in the lot were from dynasties of the mid 600's through ~ 1500 AD. These were clearly bronze in composition and all the coins cleaned up fairly well after soaking in concentrated Acetic Acid for about a week or two.
These coins were traded regularly in that region for hundreds of years, and little attention was given to dates of coinage as much as it was essential to trade upon the basis of intrinsic trading value of the coins.
The reason I have knowledge of the dates of the Oriental coins is that I presented a couple of them to Chinese business partners as gifts and they were able to translate the inscriptions which indicated the dynasty.
So back to the Ausssie find, I think discoveries like this may be more common than is typically broadcast, but 15 minutes of fame + an opportunity to take a swipe at British imperialism is the kind of a thing some folks are inclined to do.
FReegards!
