I think such continued circulation of such small 
denomination coins is believable. I remember finding worn 
first century Roman coins in fourth century sites. The 
shortage of specie was an endemic problem in the 18th and 
well into the nineteenth century.More recently, I remember 
as a student in England in the 1960's getting a halfpenny of 
William IV in change! Perhaps its Gresham's Law, good 
coinage (silver of fairly trustworthy weight and fineness) 
driving poorer coins out of circulation.Atany rate Spanish 
colonial coinage was the lingua franca of commerce for a 
long time. dave O.