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Fabrication of Platinum-Gold Alloys in Pre-Hispanic South America: Issues of Temperature and Microstructure Control.

Published online by Cambridge University Press:  28 February 2011

Carol A. Handwerker ,
Heather N. Lechtman ,
Ryna B. Marinenko ,
David S. Bright  and
Dale E. Newbury
Carol A. Handwerker
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899.
Heather N. Lechtman
Affiliation:
Massachusetts Institute of Technology, Cambridge MA 02139.
Ryna B. Marinenko
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899.
David S. Bright
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899.
Dale E. Newbury
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899.
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Abstract

Platinum and platinum-gold metallurgy was fully developed by smiths in the Esmeraldas-Tumaco Pacific coast area of present day Ecuador and Colombia long before the arrival of Europeans in South America and centuries before platinum metallurgy became practicable in the Western world. Using gold to sinter together nuggets of native placer platinum, then alternately working and annealing the resultant solid, these South American smiths produced hard, fairly homogeneous platinum-gold alloys of a range of colors for fabrication into items of adornment, and small tools, such as needles, tweezers, awls, and fishhooks.

The microstructures and compositions of sintered Pt-Au objects from La Tolita, Ecuador, and of experimentally simulated Pt-Au alloy samples were analyzed using new electron microprobe microanalysis (EPMA) techniques and data from the Pt-Au phase diagram in an effort to determine the fabrication temperatures used by Pre-Hispanic South American smiths. A comparison of EPMA results from the simulated materials with the corresponding results from the La Tolita Pt-Au objects suggests that the Pt-Au objects were never heated as high as 1100°C and probably never contained a liquid phase. As illustrated by this comparison, the qualitative and quantitative information provided by these new digital acquisition and display techniques far exceeds what conventional line scan and x-ray dot maps could provide.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 185: Symposium G – Materials Issues in Art and Archaeology II , 1990 , 649
Copyright
Copyright © Materials Research Society 1990

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