According to Guinness world records, the largest coin hoard ever found is one of 80,000 Roman coins in Brescello, Italy, in 1814 (coinsweekly says 1714). However, I stumbled across this Independent article from 1994 which refers to the Mirzakah II find of 1992-94:
A MILLION ancient silver coins - the second-largest hoard ever found - is likely to be melted down to make tourist trinkets because nobody wants to buy them.
It is understood that it consists of three tonnes of mainly silver coins, and 100 kilos of solid gold plates and jewellery.
Confirming the accuracy of this report is difficult; this is Afghanistan, so it's very complicated (warlords, plunder, illicit trading etc.) and I doubt if anyone will ever know how big this hoard is, or how much of it has been destroyed. Nonetheless, this UNESCO report by the numismatist Osmund Bopearachchi does seem to confirm that the find is much bigger than the Brescello one:
This is one of the largest ancient coin deposits ever attested in the history of mankind....According to my inquiries, it must have consisted of three to four tons of gold, silver and bronze coins, in other words about 500,000 specimens.
The number of coins can only be guessed at which probably why (as Orangesandlemons points out in his comment) Guinness world records doesn't acknowledge it.
In 2017, another huge find was reported in China:
A staggering 5.6 tons of Song Dynasty coins...
...the total number of coins was tallied at approximately 300,000 pieces.
If correct, this is bigger in terms of weight but smaller in terms of number of coins.
Both The Independent and Bopearachchi reports state that the Mirzakah II find is not the largest ever; these reports pre-date the China find so they must be referring to something else.
As Brescello doesn't seem to be the answer, what is the largest ever coin hoard or deposit found? Is there anything that surpasses any of these finds either in weight of coins or the number of coins found?
I am particularly interested in the large find (or finds) which The Independent and Osmund Bopearachchi alluded to (i.e. pre-1994).
All highlighting is mine.