The Reduction Welding Technique Used in Pre-Columbian Times: Evidences from a Silver Ring from Incallajta, Bolivia, Studied by Microscopy, SEM-EDX and PIXE


A pre-Columbian silver ring from Incallajta, Bolivia, recovered from an archaeological excavation is composed of a thin sheet of silver bent to form the ring. Two small wires in the shape of the infinity sign are joined to the surface of the ring. Four green stone beads were laid inside the four cavities formed by the wires. Energy dispersive spectroscopy (EDX) and Particle Induced X-rays Emission (PIXE) analyses of the beads proved that they were turquoise. Examination with a stereoscopic binocular microscope indicated that the two wires could have been soldered to the ring by reduction welding, because copper corrosion products were found in the interface of the welding, similar to those seen on two modern silver objects from Indonesia, decorated with granulation. Since reduction welding is a technique not reported before in pre-Columbian metallurgy, further analyses were carried out to prove that it was used here. Thus, the ring was analyzed with Scanning Electron Microscopy (SEM-EDX) and external beam PIXE, showing with certainty that the copper content in the area of the welding was higher than in any other part of the ring, with increasing copper amounts towards the center of the weld.

This is a preview of subscription content, access via your institution.


  1. 1

    M.A. Muñoz Collazo, 2006. Gestión Participativa del Patrimonio: Un caso Boliviano, Cuadernos de Antropología y Patrimonio Cultural 4. INAH-CONACULTA, Mexico, 3-47.

  2. 2

    M. A. Respaldiza & J. Gómez-Camacho (eds.), 1997. Applications of Ion Beam Analysis Techniques to Arts and Archaeometry, Universidad de Sevilla, Sevilla.

    Google Scholar 

  3. 3

    J.L. Ruvalcaba Sil. 2005. Analysis of Pre-Hispanic Items from Ancient America in X-rays in Archaeology, M. Uda, G. Demortier, I. Nakai, coord, Springer, Dordrecht,123–149.

    Google Scholar 

  4. 4

    Ch.C. Di Peso, J. B. Rinaldo and G. J. Fenner, 1974. Casas Grandes. A Fallen Trading Center of the Gran Chichimeca. Vol. 7 Stone and Metals. The Amerind Foundation Inc., Northland Press, 500–532.

  5. 5

    R.J. Gettens, 1963. Mineral Alteration Products in Ancient Metal Objects in Recent Advances in Conservation, G. Thomson, Editor, Butterworths, London, 89–92.

    Google Scholar 

  6. 6

    G. Nestler, E. Formigli, 2004. Granulazione Etrusca, Un’antica tecnica orafa, Nuova Immagine Ed., Siena.

  7. 7

    L. Beck, S. Bosonnet, S. Réveillon, D. Eliot, F. Pilon, 2004. Nuclear Instruments and Methods B 226, 153–162.

    CAS  Article  Google Scholar 

  8. 8

    T.B. Massalsi, 1992. Binary alloy phase diagrams, ASM International, Ohio, 29.

  9. 9

    J.L. Ruvalcaba Sil, L. Bucio, M.E. Marín & A. Velázquez, 2005. Estudio por XRD y haces de iones de teselas de un disco de turquesas del Templo Mayor de Tenochtitlán in La Ciencia de Materiales y su Impacto en la Arqueología. Vol II, Academia Mexicana de Ciencia de Materiales A.C., D. Mendoza, J. Arenas y V. Rodríguez coord., Ed. Lagares, México, 95-11.

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Montes, L.T., Ruvalcaba, J.L., Anaya, D.M. et al. The Reduction Welding Technique Used in Pre-Columbian Times: Evidences from a Silver Ring from Incallajta, Bolivia, Studied by Microscopy, SEM-EDX and PIXE. MRS Online Proceedings Library 1047, 201 (2007).

Download citation