Is This Chinese Coin With Authenticity Common?

Ok thankyou

Looks like it has glue on the back. You might want to take it out of the holder and soak in acetone to remove the glue residue.

The certificate claims this coin comes from the Palmer River goldfields in north Queensland, just inland from Cooktown; it was presumably sold in a tourist trap in Cooktown or Cairns, since there's no tourist shop at the actual goldfields. I have seen these particular certificates sold by coin dealers before.

As for the coin itself: despite its age, it is quite common, and almost certainly genuine, although whether it actually was found on the goldfields site or not is impossible to prove; one would tend to assume that a local historical society wouldn't lie about such things. But you can purchase coins just like it, fully identified but without the certificate, for less than $10.

Oh Spence, you spoil all the fun!

Yeah... chronologically speaking, it's the equivalent of an English convict carrying a long cross penny.

That said, the style of Chinese coinage didn't change that much since 1125 AD, so it's perfectly possible that some Song cash (hoard finds?) were still circulating back then, being mistaken for Qing cash. Similar stories are, in fact, known in Europe (stuff like Roman coins with 17th century Spanish counterstamps).
It does seem extremely unlikely, however (as in, such coins would be a very small minority, and it's terribly unlikely that one of them would be found on the fields).

Then again, nowadays, if a Northern Song coin was actually found in Australia, it would probably be a newspaper item and invite discussions of Chinese colonization of Australia. I doubt they would just calmly CoA it just as if it came from the 19th century.