20 Ouguiya

Mauritania's currency has operated outside the CFA franc zone since independence in 1973, when the ouguiya replaced the CFA franc at a rate of 5 ouguiya to 1 khoum — itself a subdivision retained from older Islamic monetary tradition. The trimetallic construction of this issue reflects a broader trend among West African central banks to deter counterfeiting through compositional complexity rather than security printing, a logical priority for a high-denomination circulating coin in a cash-dependent economy.