Sandwich structures in the Etruscan-Padan type pottery

The sandwich (black core) structure in the production of Etruscan-Padan type pottery was investigated. Petrographic, X-ray diffraction (XRD) and Mossbauer data showed that colour changes from core to margin are related to differences in both Fe oxidation state and abundance of maghemite, hercynite and hematite. The occurrence of maghemite and hercynite and the higher quantity of Fe(II) in the cores suggest poor oxygen diffusion in the potsherds during firing. This is congruent with the occurrence of high fractions of paramagnetic Fe in octahedral sites, located in the amorphous phase probably derived from chlorite breakdown, and with the wide range of grain-size distribution of oxidic particles, indicated by the slowing down of superparamagnetic relaxation as temperatures are lowered.

[1]  Owen S. Rye,et al.  Pottery Technology: Principles and Reconstruction , 1981 .

[2]  Enver Murad,et al.  Clays and clay minerals: The firing process , 1998 .

[3]  I. Shimada,et al.  The role of small particles in the study of archaeological ceramics , 1992 .

[4]  N. N. GREENWOOD,et al.  Mossbauer Spectroscopy , 1966, Nature.

[5]  R. Howie,et al.  An Introduction to the Rock-Forming Minerals , 1966 .

[6]  Rolf Kreimeyer,et al.  Some notes on the firing colour of clay bricks , 1987 .

[7]  J. G. Stevens,et al.  Mössbauer mineral handbook , 2005 .

[8]  J. Molera,et al.  The colours of Ca-rich ceramic pastes: origin and characterization , 1998 .

[9]  G. M. da Costa,et al.  Mössbauer studies of magnetite and Al-substituted maghemites , 1998 .

[10]  B. Watier.  Picon (Maurice), Introduction à l'étude technique des céramiques sigillées de Lezoux, 1973. (Centre de recherches sur les techniques gréco-romaines, n° 2.) , 1982 .

[11]  Y. Maniatis,et al.  Examination of ancient pottery using the scanning electron microscope , 1975, Nature.

[12]  Y. Maniatis,et al.  Effect of Reducing Atmosphere on Minerals and Iron Oxides Developed in Fired Clays: The Role of Ca , 1983 .

[13]  R. Wessicken,et al.  CAMPANIAN POTTERY; THE NATURE OF THE BLACK COATING , 1981 .

[14]  G. M. da Costa,et al.  Influence of Nonstoichiometry and the Presence of Maghemite on the Mössbauer Spectrum of Magnetite , 1995 .

[15]  L. Maritan.  Archaeometric study of Etruscan-Padan type pottery from the Veneto region: petrographic, mineralogical and geochemical-physical characterisation , 2004 .