The Campo del Cielo strewn field in Argentina's Gran Chaco Gualamba region was first officially documented by Spanish colonial authorities in 1576, though indigenous accounts preceded that by centuries. The iron-nickel fragments embedded in these coins are genuine meteorite material from an impact estimated at 4,000–5,000 years ago, incorporating actual extraterrestrial iron into a legal-tender silver issue is unusual enough, but the Campo material is particularly well-documented — individual named specimens have been catalogued since the 19th century.
The Campo del Cielo strewn field in Argentina's Gran Chaco Gualamba region was first officially documented by Spanish colonial authorities in 1576, though indigenous accounts preceded that by centuries. The iron-nickel fragments embedded in these coins are genuine meteorite material from an impact estimated at 4,000–5,000 years ago, incorporating actual extraterrestrial iron into a legal-tender silver issue is unusual enough, but the Campo material is particularly well-documented — individual named specimens have been catalogued since the 19th century.