Potosí Silver Piece of Eight (Real de a Ocho)

Timeline

1. 1572–1590Royal Mint of Potosí · BoliviaIn 1572 Philip II decreed the establishment of a royal mint (Casa de Moneda) at Potosí to standardize American silver coinage and deliver taxes directly to the crown. The mint used water-powered screw presses to strike refined silver, obtained by amalgamation, into standard-weight pieces of eight. The obverse bore the royal arms, the reverse a globe and pillars ('Plus Ultra'), becoming a credit mark recognizable in global markets.
2. 1590–1620Manila–Acapulco route · New SpainFrom the late 16th to early 17th century, Potosí silver flowed steadily to China via the Manila galleons: Ming China's huge demand for silver (due to the commutation of taxes into silver) made it the most sought-after trade currency. Meanwhile the coins flowed across the Atlantic to Europe, paying the Spanish Empire's troops and debts, and further into the trade circuits of the Ottoman Empire and India. Potosí silver became the world's first truly global currency.
3. 1621–1630Potosí silver mining district · BoliviaBetween 1621 and 1630 the Potosí mint remained the largest minting center in the Americas, producing hundreds of tons of silver annually, with coins flowing into the European markets of the Thirty Years' War, the spice trade of the East Indies, and the Chinese silk market. However, as ore grades declined and mercury supplies tightened, some mint operators began adulterating coins with copper and lead to reduce silver content (called 'macuquina' or 'cob coin'), triggering a major currency scandal in the 1650s that exposed the limits of imperial oversight of frontier mints.
4. 1810–1820Potosí · BoliviaThe Latin American wars of independence (1810–1825) interrupted the Spanish Empire's silver minting system. After Bolivian independence (1825), the Potosí mint switched to striking republican currency, ending the piece of eight's mission as an imperial currency. But its legacy left a deep mark on global monetary history: the word 'dollar' derives from the Bohemian Thaler, which long circulated at parity with the piece of eight in global markets.