Since at least 1742, the mineralogical collection of the Muséum National d'Histoire Naturelle (MNHN) in Paris has hosted, under the reference number 22.U, a biconvex lens-shaped obsidian artifact, also described as a mirror, measuring 250 mm in diameter and finely polished on both faces. It has usually been ascribed to the shipment sent by Hernán Cortez in 1522 to the Emperor Charles V, which was captured by a French privateer. We investigated the object using modern techniques. The elemental composition of the obsidian determined by the particle induced X-ray emission (PIXE) method showed that the raw material originates from the Mullumica deposit (Ecuador). Documentary investigations revealed that the lens (renumbered No. 176.101) was sent in 1737 from Quito, Ecuador (at that time part of the viceroyalty of Peru), to France by members of the Godin–La Condamine geodesic expedition (1735–1743). The mirror is thus among the rare Ecuadorian archeological or colonial artifacts to have reached the Old World during the eighteenth century.
