17th(?) Century Chinese Cash Coin

Sap- Thanks! Is there any way of determining the date of fakes/emergency coins of this sort? Also, while I know that a lot of Chinese cash coins circulated in Vietnam (and was the basis of their own cash), why is it that they would have copied a Chinese design rather than make provisional currency similar to what what being produced in Vietnam? Finally, though I did pull this from a 25 cent bin, do you think that this coin has any value?

I think that this is just the normal, Q'ing Dynasty Hu-Pu Revenue Board Reverse.

DCH & Sap - But would this not be a kind of contemporary fake used due to a lack of official currency in circulation (much like American Colonial Coins)? If so, is this coin totally worthless or has it some possible value? Also, do either of you know what the possible date of this coin could be?

It's not "worthless" - it's just not worth much. Because we have no idea when, where or why it might have been made, and the chances of ever knowing much more about it are slim. Maybe if you ran it through an XRF analyser and did a comparative trace metal analysis, you could find out where the copper came from, but for now all we can say for sure about it is that it was made sometime after 1796, and most likely either in Yunnan or somewhere where Yunnan coins were common. Since Vietnam is just south of Yunnan, my original assumption is still likely. It may even be a piece of relatively modern "funeral money", with the "ageing" caused by fire damage, though it doesn't really look like fire damage, from your pics.