Grouping of sherds

The Hesi Ceramics. As expected, the materials from Tell el-Hesi revealed a large group of sherds with the pattern fitting that of the coastal plain clay. Of the 225 sherds analyzed, 52 belong to this group (Table IV). These were the usual store jars, cookpots, bowls, cups, jugs, etc.,... 

Activation analysis of selected groups of sherds of typically Oaxacan and Teotihuacan ceramics has shed some light on the question of the Oaxacan presence at Teotihuacan and the related concept of long-distance trade between the two centers during early Classic times. Studies of Preclassic Tlatilco figurines reveal them to have been locally manufactured. 

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. 

To establish the relative internal consistency of the data, the large group of sherds from Dalma Tepe was somewhat arbitrarily divided unequally into two groups. The data for the first 25 archaeologically chosen sherds (representing a minimum statistically reliable number of sherds and the sherds... 

The results of our analysis of the sherds from Spain which were supplied to us by F. Lister reveal that the composition of these sherds basically conforms to the same compositional pattern which characterizes the sherds from the five sites in the Dominican Republic and Venezuela. The data for the sherds from Jerez are given in Table III, and the mean compositions are given in Table II with the mean compositions for the sherds from sites in the New World. The agreement between the sherds found in the Dominican Republic and Venezuela and those found in Spain is excellent for 14 or 15 elements, the only exception being the component barium oxide. However, we frequently have observed erratic barium concentrations in related groups of sherds, and we tend to ascribe... 

We have been able to distinguish two distinctive groups of pottery among the majolica sherds excavated from Spanish sites in the New World. These distinctions are based on the examination and analysis of the paste portions of the sherds and have involved the combined use of neutron activation analysis, x-ray diflFraction analysis, and petrographic examination. Preliminary investigations of the relationships of each of these two groups of sherds to sherds of known origin have also been undertaken. There is evidence to support a Spanish source for the sherds from sites in the Dominican Republic and Venezuela and a Mexican source for the sherds excavated in Mexico City. 

A group of 29 Mesopotamian sherds, bricks, and clay tablets ranging from the fourth millenium B.C. to the Islamic era, from Ur in the south to Ninevah in the north (eight sites) had iron ranging from 4.83 to 8.28% (mean 6.48 14.4% ) and scandium from 20.9 to 38.5 ppm (mean 27.42 14.6% ). If there were no correlation, one would calculate a Sc/Fe ratio of 4.23 with a compounded standard deviation of 20.5%. If however the Sc/Fe ratios of the individual samples are calculated and the mean standard deviation of these numbers is taken, the ratio is 4.23 3.3%. 

A second example would be a group of 26 sherds assumed to be of local Hesi manufacture. The corresponding figures were iron 4.17 to 7.34% mean 5.55 16.5%, scandium 15.6 to 27.5 ppm mean 20.52 16.3%. The calculated ratio would be 3.697 23%. The standard deviation of 26 calculated Sc/Fe ratios was however only 2.1%. The small standard deviations (3.3 and 2.1% in the Sc/Fe ratio) remaining are close to that predicted for compounding errors caused by analytical technique. 

Groups of Gezer Sherds Showing Similarity to < Local Gezer Clay GZ60... 

Groups of Gezer Sherds of Unknown Clay Sources... 

The remaining pottery of the Hesi corpus fell mainly into groups of five to 12 sherds having slight variations with the general red field clay pattern (Table VIII). Attempts to pinpoint exact locations for these... 

The placement of the Mixteca polychrome sherd from Yagul in the matching group of Table IV is of special interest. To the best of our knowledge this is the first piece of technical evidence that at least some of the famous Mixteca-Puebla polychrome was produced in the Valley of Oaxaca, confirming Bernals view (24). 

However, one Oaxacan style sherd from Teotihuacan showed Oaxacan composition and thus was probably imported. Finally, the analysis of a group of six preclassic figurines and a clay from Tlatilco in the Valley of Mexico very strongly suggests that the figurines were also locally made. 

Petrographic analysis was conducted of a sample of sherds from Groups 1, 2, and 3, of the INAA paste composition groups. The petrographic study was conducted for the purpose of comparing the current INAA analysis to previous petrographic studies of Early Islamic ceramics (33). 

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,... 

We have been able to compare our samples to a small group of majolica sherds from Spain and to a reasonably large group of Precolumbian sherds from Teotihuacan. The majolica sherds from Caribbean sites agree in composition with the Spanish specimens, and those from sites in Mexico City have compositions sufBciently similar to the sherds from Teotihuacan, considering the secondary deposits of carbonates of calcium which are in the majolica sherds and not in the Precolumbian sherds. The presence of these deposits of carbonates of calcium in the majolica and their absence in the Precolumbian sherds was determined by petrographic examination and x-ray diflFraction as well as by elemental analysis. 

Optical Microscopy. The analyzed sherds can be divided, based on the nature of the temper minerals, into three main groups (1) sherds with temper of sedimentary origin (2) sherds v/ith temper of volcanic origin or (3) sherds with temper of plutonic origin. 

A scatterplot of the results, with outliers, removed, showed three groups of pottery based on their elemental composition (Fig. 8.13). The values used on the X- and T-axes of the scatterplot are based on principle components, a technique to create summary statistics that combine the results from all of the elements used in the study. Each data point on the graph represents a sherd sample from Pinson Mounds. Thus, the X- and T-axes use most of the results of the NAA measurements. The authors of the study then drew ovals around clusters of data points in the graph to distinguish three compositional groups. These ovals should encompass 90% of the data points in the group. These compositional groups should represent pottery... 

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