Compositional analysis pottery

Data treatment, tin and lead concentrations in majolica pottery production, 383-384 Defixiones. See Curse tablets Deh Luran Plain, ceramic glaze samples for compositional analysis, 424-427,434,436 137,440 Depth profiling, coating samples from Little Lost River Cave, 162-163 Detection limits in LA-ICP-MS protocol testing copper alloy analysis, 341 Wari ceramics elemental analysis, 353-354/... 

In Chapter 5, Olin and Blackman explain that differences in the chemical compositions of pottery are caused by both the use of temper and by chemical and mineralogical differences in the source of the clay. Olin and Blackman report on the continuation of their studies of majolica (a common earthenware pottery) from the Spanish Colonial period in Mexico. They used INAA as well as microscopic examination of the minerals to show that majolica produced in Spain could be distinguished from that produced in Mexico. Volcanic temper was present in the ceramics produced in Mexico, and the chemical analysis of these local ceramics suggested different production centers in Mexico. The discovery of a chemically distinct group of sherds added to the typological classifications of this pottery. 

The concept of modeling tends to limit discussions of a best number or group of elements to use in compositional analysis (cf. 65, 66). What may be useful for one problem may not be useful for another. For example, at the global level of analysis, chromium concentration is an important regionally sensitive discriminator of ancient Maya pottery in the southwestern lowlands of Chiapas, Mexico. Yet, at the intraregional level of investigation, the range of variation frequently confuses rather than contributes to the local level of refinement. 

X-ray spectroscopy is also a useful tool when used in combination with a SEM. The SEM uses very short-wavelength, high-energy electrons, commonly exceeding 15,000 V, to stimulate X-ray emission much as an incident X-ray beam would. When an X-ray detector is coupled to an electron microscope, a compositional analysis of very small areas, only a few microns wide, is possible. One application is the identification of the mineral grains that are found in complex materials such as prehistoric pottery, which is particularly useful for identifying small mineral grains in complex matrices such as tempered pottery. 

Any given analyzed sample of pottery is a small subset of a larger ceramic system. Pottery is formed from clays and nonplastic constituents according to shared customs of the local pottery-making group as well as idiosyncratic or stochastic effects. The compositional profile that is derived from the chemical analysis of a ceramic sample, therefore, is a weighted expression of both natural and cultural constraints. 

In addition to the archaeological material, majolica sherds were obtained from two modern factories in Puebla La Trinidad and Santa Maria. Both of these potteries use a clay body blended from a mixture of equal amounts of a black volcanic clay and a white marl obtained from the immediate area around Puebla (4), Samples from these sherds were analyzed by neutron activation analysis and the data used to represent a Puebla composition. 

On the basis of the compositions obtained by neutron activation analysis two distinctive groups of pottery have been identified from the majolica sherds excavated from Spanish sites in the New World. The principal sites yielding majolica sherds analyzed in this project include Isabela, La Vega Vieja, Juandolio, and Convento de San Francisco in the Dominican Republic Nueva Cadiz in Venezuela and excavations in Mexico City at the Metropolitan Cathedral and for the Mexico City Metro transportation system. Concentrations of NazO, KzO, BaO, MnO, FezOs, RbzO, CszO, LazOs,... 

It is logical to consider whether the majolica sherds which were found in Mexico City could have been fabricated of local clay. Fortunately data on clays and related pottery from the Valley of Mexico has been collected at Brookhaven National Laboratory over many years. The ceramic material, which had previously been anlyzed by Harbottle and Sayre in collaboration with other investigators, consisted of Precolumbian artifacts. The pottery and the clays from two archaeological sites within the Valley, Teotihuacan, and Tlatilco were all basically similar in composition, although the clays and pottery from the two separate sites could be diflFerentiated through a subtle multivariate statistical analysis. It is likely that the entire Valley of Mexico is underlain with clay bed of moderately uniform trace impurity composition, and hence if the composition of the Mexico City majolica sherds was similar to that of ceramics and clay from Teotihuacan or Tlatilco, it would be probable that the majolica was fabricated from clays originating somewhere within the Valley of Mexico. 

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