During the 3rd millennium BCE, gold and silver were used primarily for decoration, ornamentation, and as a symbol of wealth (Ex. The Royal tombs of Ur). The Babylonian invention of the steelyard scale allowed accurate measurement of weight, and this facilitated a monetary revolution, since gold and silver could now serve as units of account. The development of a formal monetary system and coinage didn't exist until about 700BCE. So, the penalties and prices before 700BCE refer to specific weights of metal which could include silver, gold, brass, and iron.
According to the Babylonian system of weights:
(30 kg) = 60 minas,
cost 2.6 to 16 grams....1 gerahs to 2 shekels
One slave was purchased for 10 shekels... @ 40 days of work
Mesopotamia after 1780BC
The Code of Hammurabi c.1780BC dictated a number of fines, fees, prices and wages, complete text and commentary at http://fordham.edu/halsall/ancient/hamcode.html .
of a house received 2 shekels per sar (36 square meters), with doors and
other woodwork apparently not included (law 228).
Babylonian medical fees laws 215, 216, 217, 221, 222 and 223
Credit and finance were well established during Bronze Age Mesopotamia, and there is at least one example of a complete credit collapse in 1788BC.
See a Brief History of World Credit and Interest Rates http://peicommerce.com/RESEARCH/ECONOMY/WRLDINT1.HTM