Salt
Salt is an essential part of the human diet-so much so that many cultures have
used it as a form of payment. In Africa, merchants and consumers were adept at
dividing their portions of salt in order to make exact payments. If chunks
eventually became very small they could be used to flavor food.
Salt bound in bamboo, Sierra Leone (early 20th
century). The binding was of a fixed size and allowed the salt to circulate in
standard units.
Rock-cut
salt, Ethiopia (early 20th century). In this part of Africa, the value of salt was
calculated in Maria Theresa thalers at rates that varied by supply
(see Case 8 for a coin of that type).