Extremely  fine green diorite duck weight: probably on the qedet standard

50mm long

Weight = 52.7g

On  the  more standard scale of  1 shekel = 8.33g this finely made duck weight is very close to 1/10th of a Mesopotamian Mina or  6 1/3 shekels.  But in general weights of this size are probably multiples of whole shekels and not fractional shekels,  so one could call it a  call this a six-shekel weight. But the shekel standard varied from time to time and place to place, even nearby cities may have had slightly different standards. 

At 8.78 g. per shekel this weight could really fall in either  the Mesopotamian shekel or the Egyptian  qedet standard.  The green diorite of which it is made suggest an Egyptian or Levantine origin.  A qedet normally is a heavy Babylonian shekel standard (averages around 8.8 /8.9 g ).  Neo-Babylonian weights tend as well to fall within that range, and are certainly heavier than earlier pieces  (Whereas a Sumerian example tends to be around 8.2 g and a later Old Babylonian example would be a bit higher at around 8.4 g.) The weights of the qedet unit range from 8.81 g  (fixed by Petrie as the lowest limit) to 10.11 g. This gives an average weight of 9.46 g.

I have discussed this weight with several collector dealers and the final view is that it  is Neo-Babylonian and was actually carved ( in Egyptian diorite)  on a qedet standard rather than a shekel standard - with possible origins  in the Holyland and not in Babylonia itself.