With the very little Spanish that I know and some
dictionaries and textbooks, I have been doing the
best I can to read the article by Lechtman (1997)
about the bronzes of the Horizonte Medio of the
South American Andes. One of the things that I
noted was a grouping of bronze artifacts at Tiwanaku
and Lukurmata consisting of a copper-arsenic-nickel
alloy. The nickel content of this alloy ranges from
about 1.4 to 3.6 percent.
Looking at other papers that give detailed analyses
of Andean copper ores, I find that the nickel in different
ores is typically not detectable and at most around 70
to 300 ppm. Other analyses give nickel content for
copper ores as ranging from 0.002 to 0.006 percent
nickel. These low figures suggest that the nickel isn't
being concentrated from the ores. I haven't found
anything in either the smelting process, e.g. Lechtman
and Klein (1999), or would be added that would
account for the "high" nickel content of the Cu-As-Ni
alloy.
What could have been the source of the nickel in
this Cu-As-Ni alloy?
References
Lechtman, H., 1997, El bronze arsenical y el Horizonte
Medio. in Varon Gabai, R., and Flores Espinoza, J., eds.,
pp. 153-186, Arqueologia, Antropologia e Historia en
los Andes: Homenaje a Maria Rostworowski. Instituto
de Estudios Peruanos, Lima Peru.
Lechtman, H., and Klein, S., 1999, The production of
copper-arsenic alloys (arsenic bronze) by cosmelting:
modern experiment, ancient practice. Journal of
Archaeological Science. vol. 26, no. 5, pp. 497-526.
NOTE: I am still waiting on interlibrary loan for
Lechtman's 1998 article in "Metallurgica Antiqua."
Yours,
Paul
Paul V. Heinrich
LGS-LSU
P.O. Box G
University Station
Baton Rouge, LA 70893-4107
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