Mark Peterson of the University of Iowa has this nice article at Common-place putting the Massachusetts silver coin in historical context. This is the earliest coin minted in the American British colonies. They were purposely underweight to keep them from being sent out of the colonies. Petereson doesn’t mention this, but these coins bore the date “1652” though they were minted until the 1680s in order to hide the fact that they were still being produced even after the restoration of Charles II.