Silver from the Americas may have entered the Spanish economy later than thought

After they conquered America in the 16th century, the Spanish exploited the considerable silver resources of Peru and Mexico. Every year, nearly 300 tons of silver were extracted from New World mines. The result was an intensive production of silver coinage minted in Peru or in Mexico. These coins were imported on a massive scale into Spain and then, once in Europe, were melted down before being re-minted in Spain. Silver coins minted in the Americas and those produced in European mints are therefore indistinguishable to the naked eye. Historians consider that this flood of New World coinage began in the 16th century and that it directly contributed to the long period of inflation that affected Europe from 1520 to 1650 (the "Price Revolution"). However, these interpretations, established on the basis of historical data, do not allow the quantities of metals imported after 1492, let alone those already present in Europe, to be estimated precisely.

In order to understand the economic influence of "American" metals at the time, a team of French geochemists(1) set out to determine the provenance of coinage circulating in Spain after 1492 using quantitative analytical techniques, independent of historical data. To do this, they measured the isotope ratios(2) of silver (109Ag/107Ag), copper (65Cu/63Cu) and lead (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) in different silver coins which, although mainly composed of silver (more than 90%), also contain a little copper (around 7%) and lead impurities. Thanks to recent progress in mass spectrometry and a specific analysis protocol, the researchers were able, for the first time, to detect the isotopes of silver with sufficient precision. Combined with those of copper and lead, they reflect the isotopic composition of coinage. In this way, the researchers compared the isotopic composition of 91 coins from various epochs and origins: antique and medieval coinage representative of European minting before 1492 and two types of coins dating from after 1492 (16th, 17th and 18th centuries). The first type was minted in Mexico or in Peru, while the other was Spanish coinage, whose provenance needed to be elucidated by the researchers.

The researchers firstly demonstrated that Andean and Mexican coinage dating from before 1492 has three distinct isotopic compositions. An important finding, as it signifies that isotopic composition can help to determine the provenance of the metal used in such coins.

As regards the Spanish coinage, two groups were identified. The first, dating from the 16th and early 17th century(3), does not have a signature that ties in with Mexican and Andean coinage. This result suggests that metals from Spanish colonies had not yet been introduced into Spain at that time. Consequently, the "Price Revolution" may not have been directly linked to the massive influx of these metals in Spanish coinage. However, the absence of these metals in the Spanish economy in the 16th and early 17th centuries is not sufficient to preclude their possible role in the "Price Revolution": the influx of metals from the New World may have had a macro-influence on international markets, which could explain the inflation that occurred in Spain. Another finding is that Spanish coins minted under the reign of Philippe V (1700-1746) all have a purely Mexican signature, signifying that they were made from metals mined in Mexico. Thus, it took almost 80 years (from 1621 to 1700) for coins of Mexican provenance to completely replace those produced in Europe in the Spanish money supply. The researchers are now seeking to assess the importance of influxes of American metals on a European scale, particularly in the United Kingdom.

Notes

1 -- Laboratoire de Géologie de Lyon: Terres, Planètes et Environnement (CNRS/ENS de Lyon/Université Claude Bernard Lyon1)

2 -- Two isotopes of a same element do not have the same number of neutrons. They have the same number of electrons and protons and thus display the same chemical properties.

3 -- Under the reigns of Charles V (1516-1556), Philippe II (1556-1598) and Philippe III (1598-1621) of Spain.