Lead isotope analysis debunks legend of Dutch basin made entirely from Spanish treasure fleet silver

A study by Dr. Joosje van Bennekom and her colleagues aimed to determine the provenance of the famed silver basin supposedly made of Spanish treasure fleet silver captured by the Dutch West India Company (WIC) in 1628. The work is published in the Journal of Cultural Heritage.

In 1628, Admiral and Commander Piet Heyn (1577–1629) was ordered to intercept the returning Spanish treasure fleet laden with silver, gold, pearls, spices, pigments, crucifixes, etc.

At the time, the silver onboard was worth 11.5 million guilders, which is comparable to 56.4 billion euros today.

Today, the silver basin is part of a set, together with an ewer, both supposedly made from treasure fleet silver, housed in the Rijksmuseum Amsterdam.

Upon the ewer are various hallmarks and inscriptions that provide context to its creation, including the hallmark “Fo ENRIQZ,” indicating that silversmith Francisco Enrique made the ewer. Additionally, a pictorial hallmark comprised a lowercase “o” and uppercase “M” between two pillars of Hercules. The latter hallmark indicates that the ewer dates to between 1606 and 1628.

According to the inscription at the ewer’s base in Dutch, “This ewer was derived from the treasure fleet conquered by the gentleman Lieutenant Admiral Pieter Pieters Heyn, on the 16th of September 1628.” (Original: “Dese kanne is Gekomen uyt de Siluere Vloot Verouert bijden Heer Luijt Admirael Pieter Pieters Heyn, Den 16den Sept 1628”).

The basin, by contrast, was made in a completely different style. Its hallmark refers to the city of “The Hague,” while its inscription simply states “Administrators of the patented West Indian Company at the Chamber of the Maze 1684.” The Chamber of the Maze was the governing body of the WIC.

Despite supposedly being part of a set, the basin is not mentioned in historical records until 1808, in which it is described as “a silver ewer and basin, the first found in the cabin of the Spanish Admiral when overtaking the treasure fleet by Admiral Pieter Pitersz Hein, after which the basin was later done honor.” The word “honor” suggests that the basin may have been a later addition, made to honor Heyn and the capture of the Spanish treasure fleet.

By 1878, it appeared in a popular magazine stating both the ewer and basin were made from silver captured from the treasure fleet.

To determine the veracity of these statements and determine if the enigmatic basin was indeed made of treasure fleet silver, Dr. van Bennekom and her team conducted lead isotope ratio (LIR) analysis on the basin, ewer, and reference silver from the Americas, the Dutch Republic, and various European countries.

Silver typically contains lead impurities, which can be used to determine the provenance of the silver.

The two largest silver producers between the 16th and 18th centuries were the Potosí mine in Bolivia and a series of mines in Mexico. While in Europe, the main silver mining production centers included the Bohemia/Jáchymov (Czech Republic), the Erzgebirge (Germany), the Schwaz in Tyrol (Austria), and the Hungarian Ore Mountains in Neusohl (Slovakia).

By the mid-16th century, Spanish-American (SA) silver began replacing European sources.

Dutch objects, in particular, played a significant role in tracking this transition as they often mixed various silver sources. Remelting and reusage of silver was done in all eras of Dutch (world) history, it is still done nowadays!” explains van Bennekom.

To determine if the silver used in the ewer and basin was pure SA, mixed, or pure European silver, reference artifacts with a known provenance were used.

It was determined that while the ewer was indeed made of Mexican silver, it was likely derived from the treasure fleet. The basin, despite legend, was made of mixed silver.

“In the end, it seems very logical that some mixing had to take place. Reworking SA silver in the Netherlands somehow should leave traces in the silver of the Dutch workshop,” says Dr. Bennekom.

The legend that Heyn’s basin was crafted from treasure fleet silver probably originated during the 19th century because emerging nation-states cultivated nationalism through common historical narratives and their associated artifacts.

Thus, while the ewer authentically embodies the “triumphs” of the Dutch Republic, the myth of the silver basin is a product of its time, rather than being rooted in historical fact.

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