INVESTIGADORES
CASTELLANO Gustavo Eugenio
artículos
Título:
X-ray and Scanning Electron Microscopy archaeometric studies of pigments and ceramic surface paintings from the Aguada Culture, Argentina
Autor/es:
V. GALVÁN JOSA; S. BERTOLINO; A. LAGUENS; J. A. RIVEROS; G. CASTELLANO
Revista:
MICROCHEMICAL JOURNAL
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2010 vol. 96 p. 259 - 268
ISSN:
0026-265X
Resumen:
X
ray diffraction (XRD) and scanning electron microscopy (SEM) with
energy dispersive system (EDX) were used in order to obtain
mineralogical and chemical composition of white and reddish pigments
belonging to the Ambato style of Aguada culture, found in the
archaeological site of Piedras Blancas (Catamarca, Argentina 500-1100
AD). These pigments are associated with different sectors, two of
them being related to funerary context. Due the scarce amount of
samples available, it was necessary to develop a new methodology for
their study. X-ray diffraction spectra were collected using a low
background Si sample-holder, which allows the study of small sample
amounts (few milligrams). The mineral quantifications were carried
out by applying the Rietveld method to the XRD spectra. The major
difficulties arose for reddish pigments, since they contain
iron-bearing phases, such as ferruginous clays, in which neither the
concentration of Fe+2
relative
to Fe+3
nor
the location in the lattice (occupancy factor) are completely known.
With the aim of performing quantitative elemental analysis from
SEM-EDX spectra, a special sample-holder for the small amounts of
available samples was developed. Commercial standards were used in
the quantification process and the characteristic intensities were
corrected formatrix effects. Micrographs and EDX point spectra
allowed the characterization of minor phases and particle analysis.
The Rietveld method combined with the new procedure for EDX analysis
has proven to be a suitable method for routine quantitative analysis
of small amounts of archaeological pigments.