While excavating La Isabela in the late 1980s and early 1990s, archaeologists unearthed evidence of silver extraction. They found more than 100 lb of galena, a silver-containing lead ore, as well as hundreds of pounds of slag, which, upon close inspection, contained tiny specks of silver. This, the archaeologists thought, indicated the settlers' early silver-prospecting efforts.
But one question remained: Why didn't the settlers' records mention any discoveries of ore? Thibodeau decided to compare the lead isotope ratios from galena deposits in the Caribbean with those from the galena from La Isabela. They didn't match. But lead isotope ratios from the La Isabela galena did match those of Spanish samples of the ore, leading Thibodeau to conclude that the settlers brought the material with them, probably to compare with the anticipated local ores for a rough assay of silver content.
Has a couple photos of some of the objects, too.