Punic Amphoras Found at Corinth, Greece: An Investigation of Their Origin and Technology Author(s): Y. Maniatis, R. E. Jones, I. K. Whitbread, A. Kostikas, A. Simopoulos, Ch. Karakalos, C. K. Williams, II Source: Journal of Field Archaeology, Vol. 11, No. 2 (Summer, 1984), pp. 205-222 Published by: Boston University Stable URL: http://www.jstor.org/stable/529354 Accessed: 08/09/2010 09:23 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=boston. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Boston University is collaborating with JSTOR to digitize, preserve and extend access to Journal of Field Archaeology. http://www.jstor.org
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Punic Amphoras Found at Corinth, Greece: An Investigation of Their Origin and TechnologyAuthor(s): Y. Maniatis, R. E. Jones, I. K. Whitbread, A. Kostikas, A. Simopoulos, Ch. Karakalos,C. K. Williams, IISource: Journal of Field Archaeology, Vol. 11, No. 2 (Summer, 1984), pp. 205-222Published by: Boston UniversityStable URL: http://www.jstor.org/stable/529354Accessed: 08/09/2010 09:23
Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available athttp://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unlessyou have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and youmay use content in the JSTOR archive only for your personal, non-commercial use.
Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/action/showPublisher?publisherCode=boston.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].
Boston University is collaborating with JSTOR to digitize, preserve and extend access to Journal of FieldArchaeology.
Y. Maniatis R. E. Jones I. K. Whitbread A. Kostikas
A. Simopoulos Ch. Karakalos C. K. Williams, II
Physics Department, Nuclear Research Center Demokritos, Athens, Greece Fitch Laboratory, British School at Athens Corinth Excavations, American School of Classical Studies at Athens
Among the large deposit of amphoras of the 5th century B.C. found in a re- cently excavated building at ancient Corinth, Greece, were many of Punic type, which the excavator associated with the remains in the same building of filleted fish. These amphoras were of rather uniform shape, and yet they exhibited a wide range of colors and textures. The present paper, beginning with a description of the amphoras in hand specimen, reports the characteri- zation of the amphoras by six techniques of physico-chemical analysis that has yielded information on the amphoras' technology and origin. On the ba- sis offour techniques, chemical analysis, Mossbauer spectroscopy, X-ray ra- diography, and petrological analysis, the results all point to the use of two types of clay and two general manufacturing methods, giving rise to am- phoras of contrasting physical properties. They were produced at a single or neighboring centers. The petrological results are consistent with an origin along the Atlantic coast close to the Straits of Gibraltar, either in Morocco
.
Or tpaln.
In the spring of 1977 and 1978 a surprisingly heavy concentration of clay transport amphoras of the 5th cen- tury B.C. was excavated from within the confines of a rectangular building that lies immediately east of the pit excavated in 1975.3 The greatest amount of sherds was found laid in layers in the central court of the building and within a portico along the north side of that court. In among the smashed amphoras were found pockets of fish scales, in some cases still preserving the form in which they had been sliced. Examination of the segments of scales showed that the fish had been filleted, the strips then shipped dry or in brine. Corinth was one of the
3. C. K. Williams, II, "Corinth 1977, Forum Southeast," Hesperia 47 (1978) 15-20; idem. "Corinth, 1978: Forum Southwest,'' Hes- paria 48 (1979) 107-124. For excavation of the north edge of the Punic Amphora Building, which did not, however, produce strata of discarded amphoras, see C. K. Williams, II, "Corinth Excavations, 1979," Hesperia 49 (1980) 108-111. For a detailed discussion of Corinthian amphoras from this building, see Carolyn Koehler, "Cor- inthian Developments in the Study of Trade in the Fifth Century," Hesperia 50 (1981) 449-458.
Introduction Excavation near the center of the ancient city of Cor-
inth, Greece, in 1975 uncovered, among other things, a rectangular pit filled with discarded pottery, much of which was coarse in fabric and in form generally iden- tifiable as from containers for wine and, less generally, for goods that needed to be shipped dry. 1 The remarkable fact about this pit is that it contained two relatively com- plete examples of a type of amphora that was known previously only by one example in Greece, that being from the excavations at Olympia.2 The material from the Corinthian pit was dated by the glazed pottery it con- tained to ca. 460-440 B.C.
1. C. K. Williams, II, "Corinth, 1975: Forum Southwest," Hesperia 45 (1976) 104-107; for the amphoras, see catalogue nos. 27-30, and the note at the bottom of p. 107.
2. W. Gauer, Olympische Forschungen VIII, Die Tongefasse aus den Brunnen unterm Stadion Nordwall und im Sudost-Gebiet (Berlin 1975) 67, pl. 22, no. 3, Brunnen 63 SO, a, not long before the mid-5th century B.C.
Punic Amphoras Found at Corinth, Greece: an Investigation of Their Origin and Technology
206 Punic Amphoras at Corinth: Origin and TechnologylManiatis et al.
markets for those fish, and the house in which they were found appears to be the place where the product was distributed or processed. A number of questions arise from the finding of the amphoras and fish within what now is called the Punic Amphora Building.
With whom was the proprietor of the Punic Amphora Building trading so extensively in the middle and third quarter of the 5th century s.c.? The question is resolved by a study of the amphoras recovered from the debris of the building. About 40Wo of the amphoras, by weight of sherds recovered, was Punic, 40So Chian, SSo local Cor- inthian. Various other Greek cities supplied the last 15% of amphoras, the best represented among them being the Mendean container, or vanations thereof. Amphoras from the northern Aegean are no surprise in this context, for Corinth had access to this area in the mid-Sth century B.C. through her colony, Poteidaia. The surprising fact, rather, is the large percentage of Punic material which, until the finding of the Punic Amphora Building, was almost unknown in Greece.
Which type of amphora was used for the shipping of the fish? Mende and Chios were known in antiquity for their good wines; the customary container for those wines are jars similar to those from the Punic Amphora Build- ing. Their long, slender necks make them logical con- tainers for the shipment of wine, much less so for the packing of fish, even filleted. The study of the fish re- mains from the debris of the Punic Amphora Building suggests that the Black Sea cannot be the supply area. The bream, at least, must come from the Mediterranean or from the warm water Atlantic.4 Tunny, of which re- mains were found in the Punic Amphora Building, is still fished commercially in the western Mediterranean, from Sicily to Spain, as well as in the Atlantic. Punic cities of the western Mediterranean are known to have made a livelihood from the catching and selling of fish and related products, such as garum. It is therefore rea- sonable to assume that the fish were shipped in the Punic amphoras, not in the Greek wine jars. Hole-mouthed jars may also have served for the transport of the filleted fish; the origin of this type of container is still unidentified.S The hole-mouthed jar is represented by very few ex-
4. I thank Alwyne Wheeler of the British Museum (Natural History) for the identification of the remains of the fish. For a preliminary report, see Williams, 1979 op. cit. (in note 3) 117-118, especially note 17, pl. 46.
5. C. K. Williams, II, "Corinth, 1978: Forum Southwest," Hesperas 48 (1979) 115-117, fig. 3, pl. 45. On p. 115, especially note 14, it is implied that certain examples may be native to Motya, a Punic settlement of western Sicily. Examination of the fragments of hole- mouthed jars by persons familiar, first hand, with the jars from Motya indicates that the Corinthian jars are of a finer fabric and thus were not made in the kilns of Motya.
ej cz Pigure 1. (a) Map of the
Mediterranean showing the location of some of the sites mentioned in the text. (b) Punic amphora from Corinth.
b amples in the Punic Amphora Building, and, because of its rarity here as compared with the widely scattered remains of fish, it is best to assume that, although the hole-mouthed jars may have been used to ship fish, they are not numerous enough to have been the containers for all of the fish used in the Punic Amphora Building.
Where were the Punic amphoras found at Corinth manufactured (F1GS. 1 a-b)? Numerous examples have been reported from various wrecks along the coast of Spain.6 These have been identified and grouped by form into a special class of amphoras.7 But because the finds come mainly from the sea, the find spot can only suggest that the locality of origin is in the western Mediterranean, and not necessarily on the Iberian Peninsula. In fact, a
6. R. Pascual Guasch, "Underwater Archaeology in Andalusia," IJNA 2 (1973) 1 12-1 18.
7. R. P. Guasch, "Un nuevo tipo de anfora Punica," ArchEspArq 42 (1959) 12-19.
Journal of Field ArchaeologylVol. 11, 1984 207
diography, and porosity measurements, are relatively new in ceramic studies.
Results
1. Hand-Specimen Examination
Thirty-one samples, representing the range of colors and textures of the Punic amphoras found at Corinth, were examined initially under a binocular microscope for a rough classification of the sherds. The basic criteria used in this analysis were essentially those that have been described by Peacock,9 and for the most part they are dependent upon the mineralogy of the very coarse to medium sand grains (2.0-0.25 mm). On the basis of this analysis two groups emerged, one with dark angular in- clusions and the second with light colored, rounded min- erals and rock fragments. The latter group was divided into four subgroups on the basis of color. 10
Group I' (Samples 4, 6, 9, 10, 11, 1S, and 30)
Color: either reddish brown (SYR S/3) often grading into reddish yellow (SYR 6.5/6) towards the outer surface, or yellowish red (5YR S/6) becoming slightly stronger (SYR S/8) towards the outer edge. Sample 10 was grey- ish brown (2.5Y S/2) with a mottled appearance. Hardness: very hard; feel: harsh; fracture: hackly. Inclusions: abundant; angular; moderately sorted, mostly in the size range 1.0-O.S mm. The grains consisted of colorless and light brown quartz; white quartzite and limestone; dark green minerals; and sparse, dark grey rock fragments. Surface treatment: some of the samples were coated on the exterior surface with a very pale brown slip (1OYR 813).
Group II'
Color: (a) pale yellow (SY 8/3) sometimes with a red- dish yellow core (7.5YR 8/6): samples 7, 21, 22, and 23.
(b) predominantly light pinkish brown (7.5YR 7/4) but with some red (2.5YR S.S/8): sam- ples 16, 17, 18, 19, and 20.
(c) red sometimes with a light pinkish brown core1l: samples 1, 2, 3, 5, 12, 13, 14, 24, 25, 26, 27, 28, and 29.
9. D. P. S. Peacock, ed., Pottery and Early Commerce (London 1977) 29.
10. Munsell, Soil Color Charts (Maryland 1973).
11. Munsell notation as for (b).
number of archaeological facts suggest that the amphoras were made in present-day Morocco, perhaps along the Atlantic coast at Kouass or within the neighborhood of Kouass .8
Above and beyond the three questions already asked, a certain number of questions can be posed concerning, specifically, the Punic material. Even a casual observer can note the wide range of colors and textures in this class of amphora, as well as the variety and density of inclusions used. In contrast, however, stands the shape of the container, which from the sample excavated in the Punic Amphora Building shows almost no variation or evolution in form. The variation in body shape is much less than that, for example, of the Chian containers found in the same building.
Why is there a great range in the fabric but not in the shape? Are the amphoras fired under specifications ac- cording to the product that is to be shipped in those containers? For example, is one color of clay meant to signify that it contains sea bream, while another color tunny? Or is the difference in clay the result of firing in order to make certain containers better for the shipment of fish in brine or in an oil solution, others for dried fish? Can, on the other hand, the variations indicate the dif- ference between potters' shops, kilns, or localities?
If the variation of color and fabric results from the geographical distance between the centers of production, how far apart were those centers? If these questions can be answered, even in part, the results will contribute markedly to the study of patterns of trade between the western Phoenicians and the Corinthians of the 5th cen- tury B.C.
The issues raised by the discovery of the amphoras are clearly diverse; they essentially concern two aspects of these amphoras, as ceramic containers and as objects of trade, that are both well suited to investigation by scientific techniques. The opportunity has been taken in this work to employ a wide range of techniques appro- priate to the needs of the provenance and technological examinations and to determine the extent to which the different sets of results complement or corroborate each other. Besides the established methods of analysis for the determination of chemical and petrological com- position, the other techniques employed, Mossbauer spectroscopy, scanning electron microscopy, X-ray ra-
8. M. Ponsich, "Kouass, port antique et carrefour des voies de la Tingitane," Bulletin d'archetologie marocaine 7 (1967) 369-405. See, especially, p. 376, where mention is made of kilns dated from the 5th century B.C. downward and of different techniques used in the different kilns. See also the amphora illustrated in fig. 3, III. I would like to thank Mrs. M. L. Zimmerman Munn, who visited the site, for her opinion that the fabrics at Kouass, if not the same as the Punic am- phora fabric found at Corinth, are very close in colors and inclusions to those being discussed in this article.
a E
-4 -2 0 2 4 PCA
208 Punic Amphoras at Corinth: Origin and TechnologylManiatis et al.
(d) light pinkish brown (7.5YR 7/4) with a large grey core (2.5YR N5): samples 8 and 31.
Hardness: hard; feel: rough, often powdery; fracture: hackly. lnclusions: abundant; subangular to well rounded; sorting moderate in the range 1.0-0.5 mm except 31 which was 0.5-0.25 mm. The grains consisted of colorless, grey, and brown quartz; white quartzite and limestone; fossils; and sparse white and golden mica. SuCface treatment: several examples in subgroups (a) and (b) had a slip. The surface color varied from very pale brown (1OYR 7.5/4) to pale yellow (2.5Y 8/3).
2. Chemical Analysis The chemical analyses were carried out by optical
emission spectroscopy using, essentially, the method de- scribed by Jones. 12 In view of the relative coarseness of the amphoras, samples of at least 75 mg in weight were prepared from fragments that were cleaned of slip and weathered surface. 13 The nine elements selected for mea- surement were those normally determined (in their oxide form) by the Fitch Laboratory and the Research Labo- ratory for Archaeology at Oxford in their provenance studies of pottery. It should be understood that the com- positions, which are set out in Table 1, are partial in the sense that the major element, silicon, and such minor elements as potassium, have not been determined.
Following a standardization procedure and transfor- mation of the trace element (Mn, Cr, and Ni) contents to log form, the 31 compositions were classified by two techniques of multivariate analysis, cluster analysis (Ward's method), and principal components analysis. 14
In the dendrogram of the former analysis, the two ter- minal clusters merged at a coefficient (of dissimilarity) of only 17. 1; for convenience, they are superimposed on the plot of the first two principal components (FIG. 2,
Clusters I and II); the Fe and A1 contents are the main elements loading the first principal component, which accounts for nearly half of the total variation in com- position; the Na and Ni contents dominate the second principal component (24%) and Ca the third (17%). As an independent check on the validity of the classification
12. R. E. Jones, Greek and Cypriot pottery: a reloiew of scientific studies (Athens, forthcoming) Chapter 2. This chapter also deals with the performance characteristics of the analytical technique.
13. For discussion of this point see H. W. Catling, J. F. Cherry, R. E. Jones, and J. T. Killen, "The Linear B Inscribed Stirrup Jars and West Crete," BSA 75 (1980) 60-61.
14. These, together with the RELOCATION subprogram, are part of the CLUSTAN IC package (Release 2) (D. Wishart, Edinburgh 1978).
achieved by cluster analysis, a relocation program15 was employed; only one sample (9) was reclassified.
An apparently anomalous result was obtained for 1 and 2. They were rim and lower body fragments taken from the same amphora, and yet their compositions appear in different clusters (FIG. 2). This potentially disturbing re- sult seemed to be confirmed when freshly prepared sam- ples of the two fragments were analyzed and the same discernible discrepancy in composition was again en- countered (see TABLE 1). The problem was further ex- plored by analyzing two new fragments from the same amphora; that their compositions were comparable with the earlier ones may suggest that the vessel was not made of a homogeneous clay mix. These two new samples, because they are similar to 1 and 2, are not considered further in this paper.
Visual inspection of the individual compositions and comparison of the mean compositions of the members of the two clusters (TABLE 2) certainly bear out the point that the overall variation in the composition of the am- phoras is not marked; such a result may be expected in material of common origin, the quality of whose fabric is variable. The only element that does vary widely is
15. See note 14.
PC2 ' '
o
- l
- 2
3
4
Figure 2. Plot of the first two principal components, PC1 and PC2, which account for 48% and 24% respectively of the variation in the chemical compositions. The Fe and A1 contents dominate PC1, the (- ) Na and Ni contents PC2. I and II represent the two terminal clusters in the dendrogram of the cluster analysis. Sample 9 is unplaced.
210 Punic Amphoras at Corinth: Origin and TechnologylManiatis et al.
Mn, but this element does not apparently correlate with any other, nor does it feature strongly in the principal components analysis. The significance of the two clus- ters may, therefore, appear tentative, but as we shall demonstrate below there is strong independent support for their validity from Mossbauer spectroscopy and the petrological data. The differentiation between the two clusters is attributed mainly to the variations in two ele- ments, Fe and A1. The role of these elements in the clay is wholly or partly structural, and as such they are gen- erally less informative about origin than are many of the minor and trace elements. The important consequence of this observation, admittedly based on the experience with Greek clays, is that the clusters are more likely to rep- resent related clays, perhaps tempered differently, from the same geographical region than those from distinctly separate localities. In this connection it is noted that the resemblance in the mean compositions of the two groups extends to two of the measured elements that are origin- sensitive, Cr and Ni. Having established that the com- positions are consistent with the amphoras being manu- factured at a single or neighboring centers, it is not, unfortunately, possible to progress to the stage of trying to locate their origin; this circumstance is entirely be- cause of the absence of relevant reference data from pos- sible sites in the Mediterranean. As a heuristic exercise, however, it can be confirmed, at least, that they were not made at Corinth; the Cr and Ni contents, in partic- ular, in a group of 5th century B.C. semicoarse-ware pot- tery from Corinth are significantly higher than in the amphorae (TABLE 2). Bouchard's analyses of pottew from Mogador and of Punic amphoras found at Carthage are, regrettably, too incomplete for any valuable comparison to be made.l6
3. Mossbauer Spectroscopy
Unlike other techniques of chemical analysis that have been applied to clays and ceramics, the results of Moss- bauer spectroscopy pertain only to one element, iron. The unique feature of Mossbauer spectroscopy, how- ever, is the detailed picture that it can provide about the physical and chemical state of iron in the clay.l7 This state depends on the original clay as well as the firing
16. A. Bouchard, ''Correlations entre la composition chimique et la provenance des poteries antiques," unpublished Ph.D. dissertation, University of Clermont-Ferrand (1971). The mean Cr and Ni contents of her Mogador and Carthage samples are 0.028% and 0.020% (Cr oxide) and 0.006% and 0.005% (Ni oxide) respectively. These values are not greatly different from those in Clusters I and II (TABLE 2).
17. A. Kostikas, A. Simopoulos, and N. H. Gangas, '4Analysis of Archaeological Artifacts," in R. L. Cohen, ed., Applications of Moss- bauer Spectroscopy (London 1976) 241-261.
temperature and atmosphere. Since almost every clay contains 5-10% iron, Mossbauer spectra can be readily obtained with ca. 100 mg samples.
Iron present in clays appears (a) in the form of para- magnetic ions (ferric Fe3 + or ferrous Fe2 + ) substituting Al or (less frequently) Si sites in the clay minerals and (b) in the form of magnetic iron oxides or hydroxides usually dispersed as small particles with sizes of the or- der of 100-20000 A. The paramagnetic ions produce a doublet in the central part of the spectrum. Two "quad- rupole doublets" assigned to paramagnetic Fe3+ and Fe2+ ions are indicated by the stick diagrams in the central part of the spectrum shown in Figure 3 (components I and II). Each doublet is characterized by the velocity of the center of gravity known as isomer shift and the sep- aration of the two lines known as quadrupole splitting; the quadrupole splitting of Fe2+ in clays is always larger than that of Fe3+. A six-line pattern (component III) is observed in magnetically ordered materials (i.e., mag- netic iron oxides and hyroxides in clays), and their spec- tral features (i.e., line positions) depend on the particular oxide, its particle size, and temperature of measurement. The six-line pattern usually collapses to a doublet for small particles (ca. 100 A) and high temperatures (ca. 100°K). This phenomenon is called superparamagnetism and it can be used for the determination of the particle- size distribution of the iron oxides or hydroxides.18 A
18. N. H. Gangas, A. Simopoulos, A. Kostikas, N. Yassoglou, and S. Filippakis, ''Mossbauer Studies of Small Particles of Iron Oxides in Soil," Clays and Clay Minerals 21 (1973) 151-160.
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Journal of Field ArchaeologylVol. 11, 1984 211
useful parameter in the case of measurements at room temperature is the magnetic ratio, which is defined as the ratio of the magnetic (six-line) component to the total absorption area, and it gives the percentage of iron pres- ent as bulk oxides or hydroxides. The variation of the spectral parameters, which are extracted from spectra of pottery samples as described above, is the basis of the applications of Mossbauer spectroscopy to ancient ce- ramics. Thus, for example, the quadrupole splitting of the ferric doublet depends on the firing temperature, al- though the elemental composition of the clay itself in- troduces complications. 19 What is more, the ratio of the intensities of ferrous and ferric doublets is indicative of the prevailing atmosphere during firing. Similarly, the physical and chemical states of the iron oxide phases and their interactions with the other constituents of the clay correlate with the color and texture of the pottery20 and can be associated with major parameters of the manu- facturing procedure.
We carried out Mossbauer measurements, using a con- stant accelerator spectrometer, on the amphoras at room temperature in the "as received" (ASR) state and also after refiring at 1080°C. The refiring at a high temper- ature and under controlled atmosphere is assumed to level off all the factors dependent on initial temperature and atmosphere and reveal the real properties of the clay. That is, assuming the amphoras were made of the same clay, constant firing conditions should develop the same minerals and microstructure and, therefore, the same Mossbauer parameters. Figure 4 shows some typical spectra of samples in the ASR state and after refiring at 1080°C. It can be seen that the variation in the ASR spectra is fairly random, but after refiring the corre- sponding spectra tend to fall into two categories, one displaying large particles of iron oxide, as witnessed by the high magnetic ratio, and the other showing small ones.2l Note that the samples developing the large oxide particles after refiring contain an amount of ferrous iron in the ASR state, indicating a degree of reduction in the initial firing cycle. Figure 5 shows that the amphoras separate into two groups according to the values of two Mossbauer parameters in the refired samples: the quad-
19. Y. Maniatis, A. Simopoulos, and A. Kostikas, "Mossbauer Study of the Effect of Calcium Content on the Iron Oxide Transformations in Fired Clays, " Journal of the American Ceramic Society 64 (1981) 263-269.
20. R. Bouchez, J. M. D. Coey, R. Coussement, K. P. Schmidt, M. von Rossum, J. Aprehamian, and J. Deshayes, "Mossbauer Study of Firing Conditions used in the Manufacture of the Grey and Red Ware of Tureng Tepe," Journal de Physique 35 (1979) C6:541-547; A. Chevalier, J. M. D. Coey, and R. Bouchez, ''A Study of Iron in Fired Clay: Mossbauer Effects and Magnetic Measurements," Journal de Physique 37 (1976) C6: 861-865.
rupole splitting factor of the main ferric doublet and the magnetic ratio. The latter results, in particular, separate the amphoras into two clearly distinguished groups with a possible intermediate group of four samples. This re- sult accords well with the classification of the chemical composition data (FIG. 6).
The results of the refiring experiments show that the amphoras were manufactured from at least two different kinds of clays with different refractory properties. This conclusion is consistent with the results of principal com- ponents analysis of the composition data (FIG. 2) which differentiated the groups according mainly to the struc- tural elements, Al and Fe. It had been found in earlier investigations that clays containing more than 5% Ca when fired in an oxidizing atmosphere usually develop very small iron-oxide particles above 800°C, probably as a result of the reaction during firing of iron oxide with calcium oxide and the clay minerals leading to the for- mation of new Ca-Fe-alumino-silicates.22 This process results in the breaking down of the size and quantity of the iron-oxide particles. On the other hand, non-calcar- eous clays (less than 5% Ca) develop large iron-oxide particles, presumably because the iron is less free to move about during the destruction of the clay mineral lattice with firing and in the presence of oxygen in the environment which allows the formation of large oxide particles.
In the case of the amphoras, therefore, one can say that the groups, which upon refiring at 1080°C exhibit large and small magnetic ratios, behave as non-calcar- eous and calcareous clays respectively. The situation, however, is more complicated because all of the am- phoras were found to contain more than 9% Ca oxide (TABLE 1); this problem is discussed later (see note 41).
4. X-ray Radiography This technique involves the straightforward X-raying
of the sherds; it was applied in this study to obtain in- formation about the concentration of inclusions and pores inside the clay body as well as constructional and ori- entational details.23
The radiography24 of the amphoras showed that they were well built since few cracks or large pores were revealed; no further structural details were evident. Pores and inclusions in some cases showed strong alignment parallel to the surface. The most striking feature is the
21. Maniatis et al., op. cit. (in note 19) 265-266.
22. Ibid. 267.
23. O. S. Rye, "Pottery Manufacturing Techniques: X-ray Studies," Archaeometry 19 (1977) 205-211.
24. Using a portable SCANRAY X-ray unit with a focal spot of 1.5 cm x 1.5 cm.
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212 Punic Amphoras at Corinth: Origin and TechnologylManiatis et al.
REFIRED: 10{30 C Figure 4. Mossbauer spectra taken at room temperature of 1, 2, 3 4, 6, and 9 in the i'as received state" (ASR) and after refiring at 1080°C.
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100.0
n.o .
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%.0
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-
-
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S: . 6
.
r^ww{t b7>¢---oW * W * * *
s - s
*
s
o >>--
* *
.
t ' 3
: #* sWN
> ', 3
s ' t/-;' . * , .
-.- 2
0*< ;w **My. W*
*# ' #
*i+a. :.e.* H-
*
:
*-
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:-*. *.
Figure 5. Upper: the magnetic ratio (AmlAT) values in the refired samples. Lower: the quadrupole splitting (e2qQ/2) values of the main felTic doublet in the refired samples.
0 10 20 30 40 50 60 ArnlAT (IQ80 *C}
Q70 0.80
0.90 e qa (1080 C J
n
o 2 8 a
* I \
s , 1 8 ' > , _ \
" o 29 17 26 s _/ _ \
21 19 31 25 12 " _ ;
16 1 27 23 14 24 5 s I | _ >
l 1 2 7 20 13 3 ,
' 27 , _
_ 1
_ 1 1
6 9
S - -
Journal of Field ArchaeologylVol. 11, 1984 213
variation in the concentration of dense inclusions (FIG.
7), the highest concentration of them appearing in the amphoras belonging to Cluster I, which corresponds to the group with the high magnetic ratio. This result fur-
ther consolidates the difference between Clusters I and II in terms of technology of manufacture. There are only two exceptions in this classification: 22 and 27 fall in the wrong cluster as far as the concentration of inclusions is concerned. The inclusions in the Cluster I samples, rather irregular in shape and relatively large, were probably added as filler or grit for reasons that are discussed later (see section 6 and Discussion). They appear in the X- ray film (FIG. 7) with considerably higher intensity than the background, which indicates that they were made of elements of higher atomic number than those of the clay matrix, itself consisting mainly of Al and Si with atomic numbers 13 and 14. It seems likely, therefore, that these inclusions are made of elements at least twice as heavy.
5. Petrological Analysis
Having established that two general groups of am- phoras could be distinguished by slightly different chem- ical compositions and by different manufacturing techniques, we selectively used petrological analysis in an attempt to characterize the amphoras more fully. Briefly, it may be recalled that the identification of the mineral inclusions in petrological analysis defines the geology of the raw materials that were used to produce the amphoras;25 it will become readily apparent that the
25. D. P. S. Peacock, "Roman Amphorae: Typology, fabric and origins," in Me'thodes classiques et me'thodes formelles dans l'e'tude des amphores. Actes du Colloque de Rome, 1974 (Ecole Frangaise de Rome 1977) 261-267.
PC2
3
2
o
-2 --1
-3 -
-4
- 4
O. Low Am/AT
,: Med iun Am/AT
-2 0 2 4 PC1
2: High Am /Ar
Figure 6. Comparison of the chemical compositions and Mossbauer (magnetic ratio) results. o, lv and :1: low, medium, and high magnetic ratios respectively (see FIG. S [upper}).
Figure 7. X-ray radiograph of 1, 2, 3, 4, 5, 6, and 8.
214 Punic Amphoras at Corinth: Origin and Technology/Maniatis et al.
Punic amphoras are highly suitable material for this type of analysis. In turn, geographical regions that are com- patible with the petrological data can then be suggested. The accurate and successful localization of sources, however, is dependent on several factors, which include the presence of distinctive mineral inclusions, the avail- ability of detailed geological reconnaissance in the re- gions of interest, and reference material from the possible sources.
Twenty-two samples were selected for thin sectioning, and their examination was carried out using a Swift MP 120 polarizing microscope. This was supplemented with point counting and measuring to give relative proportions of the constituents and their size. Again two groups were separated, and they are termed Groups I and II,26 the latter being subdivided into five smaller assemblages, (a) to (e).
The results of the grain-size analysis are discussed first as they concern the amphora fabrics as a whole. Thirteen samples (at least two from each subgroup) were exam- ined, 300 grains being counted in each sample. The gen- eral shape of the graph (FIG. 8) was the same in all cases except for 18. At the coarser end the cut-off points differ; Group I tends to be greater than 1 mm, whereas Group II is no greater than 1 mm and often does not reach this level. The sharp drop in the gradient in the fine-sand region reflects the small quantity of grains of this size in the samples. The steeper gradient at the coarse end indicates the addition of temper, and at the fine end the presence of abundant very fine sand and silt in the clay matrix. Sample 18 is not so well sorted, having overall a more consistent gradient owing to the greater quantity of fine sand present, and the relatively large grain sizes at the finer end of the scale than in the other samples.
Group I (Metamorphic): Samples 4, 6, 10, and 15 (PLATE la)
In thin section this fabric was characterized by its color in crossed polarized light. This was predominantly dark red, but with dark green haloes surrounding the voids. Other highly distinctive features of this group were best observed in plane polarized light at low magnification. By these means colorless garnet and strongly pleochroic chlorite and amphibole(?) were observed. The samples in this group contained significant quantities of quartz (mono- and polycrystalline), kyanite (a few examples bearing inclusions of sillimanite) and chloritoid(?) with subordinate orthoclase feldspar. Many of the minerals
26. The classification of the petrological groups, I and II, follows the same nomenclature as those of the chemical analysis, Mossbauer spec- troscopy, and X-ray radiography results. A distinction is deliberately made in the case of the hand-specimen groups which are designated I' and II'.
lll
:
I __ _ _ _ _ _ .eg11111 1 1 1 1 1
2 1 0.5 025 0.125 0.0625 0.031 0 0150 mm V.COARSE COARSE MEDIUM FINE V.FINE COARSE MEDIUM
SAND SAND SAND SAND SAND SILT SILT
Figure 8. Grain-size analysis.
were also represented in rock fragments, of which mica schist was the most abundant rock type. The matrix con- tained a great many very fine grains which were mostly of quartz, biotite and white mica, plagioclase, and some red iron oxide (probably haematite) together with scatters of lime. The majority of the inclusions were angular to subrounded.
Attention is drawn to 10 which is of particular interest because of the occurrence, in several instances, of dark brown to black opaque material which surrounded a cen- ter composed of numerous voids and a pale green (non- pleochroic) cryptocrystalline material. This material pre- sented in places second to third order interference colors and contained considerable quantities of very small, black opaque inclusions; these are thought to be an alteration product. 27
Group II (Sedimentary) (PLATE lb)
(a) Sand with lime scattered through the matrix (7 and 21).
(b) Sand with some limestone (17, 18, 19, and 20). (c) Sand with limestone and fossils (1, 2, 3, 5, 13, 14,
and 26). (d) Sand, limestone and fossils, but with some rounded
metamorphic grains (8 and 31). (e) Rounded low grade metamorphic rock fragments (11,
16, and 22). These subgroups are characterized as follows. (a) This group consisted of subangular to well rounded
grains of mono- and polycrystalline quartz, ortho- clase feldspar and sparse plagioclase (with albite twinning). The orthoclase was often cloudy and oc- casionally the presence of alteration to sericite was
27. I. K. W. thanks Dr. I. C. Freestone of the British Museum Re- search Laboratory for his discussion of this sample.
Plate l(a). Fabric 1 (low-grade metamorphic): sample 6 (width of photograph 7.3 mm). Seen in cross polarized light: white quartz, polycrystalline quartz and kyanite; yellow chlorite and amphibole(?); colorless garnet next to amphibole(?) in top right hand corner.
Plate l(b). Fabric 2b (sedimentary sand, limestone, and fossils): sample 2 (width of photograph 7.5 mm). Seen in crossed polarized light: white quartz and plagioclase; microfossils just below center, to left and right.
Journal of Field ArchaeologylVol. 11, 1984 215
noted. A few of the orthoclase grains also displayed microperthitic intergrowths. Many of the grains were covered by a thin band of lime around their circum- ference. The matrix was dark green in crossed po- larized light, contained fine-grained quartz, and abundant lime scattered in patches. Although some small grains of red iron oxide occurred, the apparent absence of fine mica in the matrix contributed to the distinct nature of the fabric of 7.
The refiring of 3 and 5, which were placed in subgroup (c), to a temperature of 1080°C resulted in a fabric very similar to (a). In fact, the main differ- ence was the absence of scattered lime in the refired samples. It is therefore proposed that (a) is a tech- nological subgroup derived from (b) or (c) as a result of the decomposition of limestone and fossiIs be- tween 675 and 950°C,28 rather than a source subgroup based on the availability of different minerals.
(b) This subgroup contained the same range of inclu- sions as (a). Many of the grains were well rounded and of high apparent sphericity (as judged only in the two dimensions of thin section). In cross polar- ized light the color of the matrix was yellow brown. The presence of well rounded grains of limestone and abundant lime scattered throughout the matrix characterized the fabric of (b). Again, grains oc- curred that had received a thin coating of lime as described in (a). The matrix also contained fine grains of biotite and white mica, possibly accompanied by phlogopite, together with red iron oxide and rutile.
(c) A close relationship with (b) was readily apparent, the most noticeable difference being the presence of microfossils (in this case Foraminifera). These sam- ples also contained well rounded grains of limestone that clearly displayed a polycrystalline structure, with individual subgrains having different optical orien- tations. The source must, therefore, have been a crystalline limestone or marble; otherwise, the color and mineral content of the fabric were the same in thin section as for (b).
(d) In cross polarized light the two samples in this subgroup differed in color and in grain size;29 one had a dark brown matrix while the other was dark green. The majority of the grains were subrounded. They consisted of mono- and polycrystalline quartz together with orthoclase and plagioclase feldspars. The latter were of varied degrees of alteration and
28. D. N. Todor, Thermal Analysis of Minerals (Abacus Press: Kent 1976) 161.
29. Sample 31 was much finer grained than any of the other Punic amphoras both in hand specimen and in thin section.
cloudiness. In some cases the orthoclase was micro- perthitic. Limestone and microfossils, accompanied by bivalve shell fragments, were common. In addi- tion, a few fragments of sandstone were noted (very fine subrounded sand in a fine silty matrix). The metamorphic minerals and rock fragments included sparse garnet, chlorite and pyroxene (augite), green and brown serpentinite, white mica schist, and phyl- lite. The matrix contained silt grains of quartz and feldspar with sparse rutile, zircon, biotite, and, pos- sibly, phlogopite micas.
(e) Like (d) the colors of the matrix in crossed polarized light differed within the subgroup; two samples were dark brown and one dark green. There was also sim- ilarity in the mineralogy between the two subgroups, especially the presence of sandstone fragments. There were, nevertheless, differences between them, the main one being the near absence of microfossils and limestone grains. This was accompanied by an in- crease in the quantity of phyllitic rock fragments, which also frequently displayed microfolds. Biotite and muscovite schists, together with garnet and chlorite, resembled the rock fragments of Group I, particularly in the case of 11 which also contained grains of augite. Serpentinite was present, containing garnet, as was a chlorite-plagioclase (with Carlsbad twinning) schist. A single rock fragment of white mica, quartz, and kyanite was recorded, as was the occurrence of two well rounded grains of cordierite and very sparse chloritoid(?).
A summary of the most important minerals and rock fragments is presented in Table 3. The proportions quoted are purely qualitative because of inaccuracies in point counting and measuring as well as the number and size of samples available. Nevertheless, the percentages of matrix to mineral and rock inclusions (greater than about 0. 125 mm) were obtained by point counting and are con- sidered to reflect accurately these proportions.
The presence of sedimentary rock fragments such as limestone, fossils, and sandstone along with rounded metamorphic grains in the same samples of subgroups II d and II e, which in some cases (notably 11) were similar to the fragments in Group I, suggest that the fabrics were all produced within the same general region. The fresh and angular grains in Group I would tend to indicate that the metamorphic source was not too far from the site of production. Too little is understood, however, about the collection and processing of the raw materials for ancient pottery production to ignore the possibility that the material may have been transported by the potters quite some distance from its site of for- mation, or indeed its site of deposition by natural agen- cies.
Table 3. The frequency of the principal minerals and rock fragments in Groups I and II.
Quartz Polycrystalline Common Sparse Sparse Sparse Common Common
Chert Sparse Sparse Sparse Sparse Sparse
Orthoclase Feldspar Sparse Common Common Common Common Sparse
Plagioclase Feldspar Sparse Sparse Sparse Sparse Common Sparse
Kyanite Sparse V. Sparse
Sillimanite Sparse
Chloritoid(?) Common V. Sparse
Cordierite V. Sparse
Garnet Common Sparse Sparse
Chlorite Abundant Sparse Sparse
Amphibole(?) Common
Pyroxene Sparse Sparse
Sandstone Common Sparse
Schist Common Common Common
Phyllite Sparse Sparse Common
Serpentinite Sparse Common
Limestone Abundant Abundant Common Sparse
Fossils Common Common Sparse
Clay Pellets Sparse Common Common Common Sparse Sparse
Matrix 80-90Wo 70Wo 70Wo 70Wo 70% 70%
216 Punic Amphoras at Corinth: Origin and Technology/Maniatis et al.
Although the metamorphic rock fragments are distinc- tive with respect to isolating different fabrics, the inclu- sions cannot be used with a high degree of confidence for provenance purposes, as most of the rock types rep- resented are extremely common. The region in which the Punic amphoras are thought (on present evidence) to have originated is either side of the Straits of Gibraltar, in southern Spain, or northern Morocco. As mentioned in the Introduction, there is already archaeological evi- dence for production of such amphoras on the Atlantic coast of Morocco at Kouass.30
The geological situation in this region is highly un- suitable for choosing between northern Morocco and southern Spain, in that the formations of the Moroccan Rif appear to take a "U'' shaped bend to the west of the Straits of Gibraltar and return to form the Betic region of southern Spain; hence the same range of rock types
appears on both sides of the Straits.3l All of the petro- logically defined fabrics could have originated on either side of the Straits, although (judging purely from the literature) the Atlantic coast would appear more likely to provide the sedimentar fabrics than the metamorphic.32
The fabrics described by Peacock33 for Roman am- phoras from production sites in southern Spain do bear an overall similarity to some of the sedimentary Punic
31. J. M. Rios, "The Mediterranean Coast of Spain and the Alboran Sea," in A. E. M. Nairn, W. H. Kanes, and F. G. Stehli, eds., The Ocean Basins and Margins: 4B The Western Mediterranean (Plenum Press: New York and London 1978) 1-65 and fig. 14.
32. H. E. Rondeel and 0. J. Simon, "Betic Cordilleras," in A. P. Spencer, ed., Mesozoic-Cenozoic Orogenic Belts, The Geological So- ciety: Special Publication 4 (London 1974) 23-35; G. Choubert and A. Faure-Muret, "Moroccan Rif," in Spencer, ed., op. cit. (this note) 37-46.
33. D. P. S. Peacock, "Amphorae and the Beitican Fish Industry," AntJ 54 (1974) 232-243. 30. Ponsich, op. cit. (in note 8).
Journal of Field ArchaeologylVol. 11, 1984 217
in the case of food-storage vessels such as the Punic amphoras.
The open or apparent porosity is defined as the ratio of the volume of the open pores to the total volume of the pieces, and in order to measure it samples of ap- proximate dimensions, 3 cm x 3 cm, were boiled in water for about four hours and left to cool overnight so that all pores were filled with water. These saturated specimens were first weighed suspended in water (Wb) and then suspended in air (Wc). Finally, they were placed in a drying oven for several hours at 140°C and the com- pletely dried specimens were reweighed in air (Wa). The open porosity was calculated from this data using the following equation.
WC - W apparent poroSlty = W - Wb
amphora fabrics, but the near absence of metamorphic material does not encourage correlation.34 Analysis of Punic amphoras from production sites, together with sur- veys in search of other such sites on the Atlantic and Mediterranean coasts, will be necessary before the origin of the various Punic amphora fabrics can be established.
Combining the results of petrological analysis and hand- specimen examination we propose the following fabrics.
Fabric 1 Group I (Metamorphic) Fabric 2a Subgroup II a (Sedimentary but reflecting a
technological division) Fabric 2b Subgroups II b and c (Sedimentary with and
without fossils) Fabric 2c Subgroups II d and e (Sedimentary-metamor-
phic with and without fossils and limestone)
The classifications derived from chemical and petro- logical analyses can now be compared, bearing in mind that there is an imbalance in the number of samples ana- lyzed in each case. The main comment to make is that the correlation between the two classifications is good. Fabric I (metamorphic) correlates with Cluster I, while the samples with inclusions of sedimentary origin, Fab- rics 2a and 2b, fall uniformly into Cluster II. The dis- tinction between Fabrics 2a and 2b (sedimentary), on the one hand, and Fabric 2c (sedimentary-metamorphic), on the other, is borne st, if imperfectly, in terms of chem- ical composition. Samples 8, 11, 16, and 31 are found within the metamorphic group of Cluster I, but 22 be- longs securely to Cluster II; the composition of 8 is un- usual for its relatively high contents of all three trace elements. Furthermore, 1 and 2, which came from the same amphora but gave anomalous chemical results (sec- tion 2), were found to be petrologically similar, both of them of sedimentary origin (Fabric 2b).
A discussion of the minerals, rock fragments, and the sources of the temper is given in the Appendix.
6. Porosity Measurements
There are two types of pores in a ceramic, the open pores, effectively capillary tubes extending to the sur- face, and the closed pores, which do not extend to the surface.35 It is evident that the open pores directly affect properties such as permeability, a highly relevant factor
34. This also applies to the Punic amphoras from Uzita; see J. H. van der Werff, "Amphores de tradition punique a Uzita," BABesch 52-53 (1977-78) 171-200. I. K. W. thanks Dr. D. P. S. Peacock for this reference and discussion.
35. W. D. Kingery, H. K. Bowen, and D. R. Uhlman, Introduction to Ceramics (New York 1976) 518-521.
The results for the Punic amphoras are shown in Table 4; the range of porosity values is 24 to 40%, those near the lower limit are produced either by fine non-calcar- eous clays at temperatures lower than 900°C or by coarser calcareous clays (which is more likely to be the case with the Punic amphoras) fired above 1050°C.36 The higher porosities are exhibited by coarse calcareous or non-calcareous clays at temperatures below 1000°C.
As far as the differences between the main clusters are concerned, the Cluster I samples, developing large iron- oxide particles and containing a high density of inclu- sions, have porosity values concentrating between 27% and 31%, while the Cluster II samples attain porosities which are much more wide-ranging. Bearing in mind that tempering usually increases the porosity, it is evident that the clays of Cluster I would have had ver low porosities if they had not been tempered.
7. Scanning Electron Microscopy (SEM)
The examination of fresh-fractured surfaces of ceramic samples under the SEM provides information of the in- ternal morphology of the clay and the degree of vitrifi- cation that develops during firing.37 An estimate of the original firing temperature can be made by combining this information either with the data from clays and pot-
36. M. S. Tite and Y. Maniatis, "Scanning Electron Microscopy of Fired Calcareous Clays," Transactions and Journal of the British Ceramic Society 74 (1975) 19-22.
37. Y. Maniatis and M. S. Tite, "Ceramic Technology in the Aegean World during the Bronze Age," Proc. 2nd Internat. Scient. Congress on Thera and the Aegean World I (London 1978) 483-492; Y. Man- iatis and M. S. Tite, "Technological Examination of Neolithic-Bronze Age Pottery from Central and South-east Europe and from the Near East," JAS 8 (1981) 59-76.
Sample Body color WoCaO Vitrif. Stage* Firing Temp. (°C) Open porosity (Wo)
Group I 4 Red-Grey 10.2 - 850-950** 27 6 Grey-Brown 9.4 V 850- 1050 27 9 Grey-Brown 9.4 V 850- 1050 27
10 Dark green 11.5 TV 1100 31 11 Grey-Brown 9.3 V 850-1050 27
Group 11 (a) 7 Green-Yellow 18.7 TV 1150 31
21 Green-Yellow 20.4 V 850-1050 38
(b) 19 Light brown 13.6 V 850-1050 33
(c) 1 Red-Brown 19.4 IV/V 800-850 33 2 Red 19.7 IV 750-800 26 3 Light brown 15.1 850-950** 33 S Red 17.5 800** 31
12 Red 19.5 IV/V 800-850 30 13 Red 15.2 IV/V 800-850 30 14 Red-Brown 16.6 V- 800-900 31
(d) 8 Grey-Brown 16.0 IV 750-800 30 31 Grey-Brown 13.6 V 850-1050 29
(e) 16 Light brown 11.0 V- 800-900 34 22 Green-Yellow 16.2 V 850- 1050 34
**Firing temperatures determined from Mossbauer spectroscopy results.
218 Punic Amphoras at Corinth: Origin and Technology/Maniatis et al.
Table 4. Technological results; vitrification microscopy and porosity values.
stage and firing temperature estimated from scanning electron
stage.39 Sample 31 had a very fine cellular microstructure which differed from the rest.
The vitrification stage, the estimated firing tempera- ture and the open porosity value of the samples are shown in Table 4. It can be seen that Group I is associated with higher firing temperatures and lower porosities, a result that accords with these samples having a cellular micro- structure of the more closed type.40 The Group II sam- ples span a wide range of firing temperatures and porosities, although subgroup (c) has consistently lower firing temperatures and higher porosities than Group I.
The colors of the amphoras belonging to Group I are darker than those of Group II; within the latter the color
39. Ibid. 486.
40. The porosity of 10 is rather high for its very vitrified micro- structure (TABLE 4); assuming there was no error in the porosity mea- surements (the available sample was rather small), the exceptionally heavy tempering of this sherd could be responsible for the result ob- tained.
tery of known morphologies or by refiring the samples and reexamining them under the SEM. In addition, the degree of vitrification present in the microstructure of a fired clay body can give an indication of its strength, hardness, and porosity.
Seventeen samples were examined under the SEM in the "as received" (ASR) form and after refiring at 1080°C so that a direct comparison could be made with the Moss- bauer results. The ASR samples showed a wide range of microstructures because of variable firing tempera- tures and differing behavior of the clays during firing. All the well fired samples exhibited a cellular type mi- crostructure characteristic of calcareous clays fired in the temperature range 850-1050°C.38 Two forms of micro- structure, however, were discernible: more open (FIG. 9a)
and less open (FIG. 9b), and their apparent porosities were found to be 34% and 27% respectively. Several samples exhibited microstructure types of the initial vitrification stage, while others had reached the total vitrification
38. Maniatis and Tite, 1981 op. cit. (in note 37) 486.
Journal of Field ArehaeologylVol. 11, 1984 219
Figure 9. (a) SEM micrograph of 22 (Group II) in the ''as received state" showing characteristic calcareous open structure. (b) SEM micrograph of 6 (Group I) in the ''as received state'' showing more vitrified and denser microstructure. (c) SEM micrograph of 9 after refiring at 1 080°C, showing coarse vitrified microstructure. White bar in each photograph represents 10F.
a
b
c
Table 5. A comparison of the classification of the amphoras according to (1) chemical analysis, (2) Mossbauer spectroscopy, (3) X-ray radiography, and (4) petrological analysis.
Mossbauer X-ray Petro- Chemical Spectros- Radiog- logical
Sample Analysis copy raphy Analysis
6 I I I I 9 I/II I I
10 I I I I 4 I I I I
15 I I I I 30 I I I 11 I I I IIe
<, < 8 I I I IId g 27 I I II u) 16 I I/II I IIe X 31 I I/II II IId *; 14 II I/II II IIc ; 19 II I/II II IIb
-
;, 2 I II II IIc O i22 II II I IIe
12 II II II 13 II II IIc 26 II II II IIc 24 II II II 18 II II II IIb 20 II II II IIb 28 II II II 2S II II II 23 II II II 21 II II II IIa 29 II II II 17 II II II IIb 7 II II II IIa 1 II II II IIc 3 II II II IIc S II II II IIc
220 Punic Amphoras at Corinth: Origin and TechnologylManiatis et al.
varies from red (low fired) to light brown (high fired). This finding is not unexpected since above 850°C, when solid-state reactions begin to take place, iron is diluted in the newly formed calcium-aluminosilicate phases, and this results in the dissociation of the red haematite par- ticles, which were formed up to that temperature, and in the bleaching of the red color.4l
The results of SEM suggest that the two groups of amphoras were the products of different ceramic tech- nologies. Group I was fired predominantly in reducing atmospheres (as witnessed by the Mossbauer results) and at higher temperatures; it contained less calcium, it pro- duced a more glassy and closed microstructure and it was heavily gritted. Group II, by contrast, displays a range of colors and firing temperatures, but the porosities are generally high, as are the calcium contents, resulting in light and soft wares.
Finally, the sherds refired at 1080°C exhibited much more vitrified microstructure (FIG. 9c) with a slight vari- ation in the extent of glass formation. These variations, however, did not correlate with the types of microstruc- ture observed in the ASk samples.
Discussion
The results of all the techniques employed, apart per- haps from SEM, point towards the existence of two kinds of clay for the production of the Punic amphoras. The classification of the samples derived from the four tech- niques listed in Table 5 is, with few exceptions, entirely consistent.
The chemical compositions determined by optical emission spectroscopy divide into two types of clay ac- cording mainly to the structural elements, Fe and Al. Mossbauer spectroscopy reveals that these two clays or groups of clays behave differently on firing at higher temperatures. The petrological basis of the two groups has also been defined: one clay contains inclusions of sedimentary origin and the other contains metamorphic temper; among the five subgroups within the former, II a, II b, and II c probably reflect temperature and minor tempering differences, while II d and II e present an interesting mixture of sedimentary and low-grade meta- morphic temper. X-ray radiography highlights the high concentration of dense inclusions in the metamorphic group. Finally, SEM and porosity measurements have provided information on the firing techniques employed, and they also suggest the existence of at least one con- sistent technology (Group I) and one or more different ones (Group II).
With these data it is now possible to correlate the classifications determined initially by hand-specimen ex- amination with those derived from the various analytical techniques, especially petrological analysis. That the two main groups, I' and II', separate according to color is a reflection of the use of two general techniques of man- ufacture either in the same or in different workshops; overall reducing and oxidizing atmospheres seem to characterize the two techniques; Group I' of the hand- specimen examination correlates well with petrological Group I. Sample 11 contains sedimentary inclusions and notably fewer low-grade metamorphic minerals than the members of Group I', but it has the characteristic dark color in hand specimen. Sample 10 is unusual, but it only appears to differ from the others in Group I' from
41. Chevalier et al., op. cit. (in note 20) 861-865; Maniatis et al., op. cit. (in note 19) 263-269.
Journal of Field ArchaeologylVol. 11, 1984 221
the technological point of view rather than in its miner- alogical composition. The subgroups of Groups II' and II also correlate well with the exception of two samples, 16 and 22, which together with 11 form II e. It is clear that the features noted in hand-specimen examination reflect with reasonable accuracy the tempering material in the pottery, and, as a result, it should be possible for the archaeologist to give a general fabric classification without the need for detailed petrological analysis. Such a classification would be useful in the field, for example, although the presence of anomalous samples argues for some caution in using it for more precise definition.
One last point concerns the contrasting physical prop- erties of the two main groups. The amphoras in Group I were fired at consistently higher temperatures (in rather reducing atmospheres) than those in Group II, and they have slightly lower Ca contents and lower porosities; that they were heavily tempered was necessary to increase their strength and durability.42 The Group II amphoras are lighter and more porous, resisting thermal and me- chanical shock better; these properties were achieved ir- respective of firing atmosphere in the temperature range 850 to 1 000°C . 43
Conclusions
The value of this study can be judged at two levels; first it has answered many of the archaeological ques- tions about the Punic amphoras found at Corinth, and second it has demonstrated an important methodological aspect of archaeological science, namely, that the data obtained from several techniques have collectively pro- duced a full physico-chemical description of this type of amphora. We have shown how the classification of this material by the provenance-oriented techniques of chem- ical and petrological analysis has been extended and strengthened by the application of Mossbauer spectros- copy and SEM. The value of Mossbauer spectroscopy in detecting the different behavior of two groups of clays should be emphasized; in addition, X-ray radiography, which has not hitherto been used much in this type of work, proved useful.
In concluding, we have established that the composi- tions are consistent with the amphoras being manufac-
42. The presence of calcium oxide contents greater than 9%, how- ever, may appear to conflict with the formation of iron oxides (de- tected by Mossbauer spectroscopy) and the consequent nonformation of calcium aluminosilicates. There are two possible explanations; either the calcite particles are large and do not participate in the solid-state reactions forming calcium aluminosilicates (Maniatis and Tite, 1981 op. cit. [in note 37] 65), or the only calcium aluminosilicate mineral formed is a more glassy body, an observation that was verified by the SEM examination of the Group I samples.
43. Maniatis and Tite, 1978 op. cit. (in note 37) 491.
tured at a single or neighboring centers. Furthermore, the coexistence of low-grade metamorphic, together with sedimentary, fragments in a number of the amphoras (Groups II d and II e) indicates that both sources of temper were used simultaneously by the same potter. Although it has not been possible to determine the pre- cise location of these centers, the geology of the NW coast of Morocco to the Straits of Gibraltar and the coast op- posite on Spain can accommodate both the clay and tem- per of the amphoras.
Wherever the amphoras were made, the nature of the two technologies is indicative that one ware was prob- ably good enough for carrying fish in oil or brine, its quality being very consistent, while the second ware was very porous, suitable only for dry contents. Although the observed range of colors among the amphoras may rep- resent no more than the variations in the firing condi- tions, it is possible that different colors were deliberately achieved in order to signify content. Furthermore, since all the fish found in the Punic Amphora Building at Cor- inth were filleted, it is possible that a portion or type of such fish was shipped dried or salted in amphoras fired in one way, while other fillets were perhaps shipped in oil or brine within amphoras produced in the same area but under different conditions. What light this reflects upon ancient tastes, menus, and national customs, how- ever, it yet to be investigated. The present findings un- doubtedly provide scope for further research.
Appendix
1. Discussion of Minerals
The quartz frequently displayed undulose extinction up to about 20°. The grains also contained vacuoles (air and liquid bubbles), and inclusions of rutile and zircon. It is possible that at least some of the very fine sand and silt-sized grains were derived from the breakdown of polyciystalline grains. The term "polyciystalline quartz" has been applied to those grains composed of several quartz crystals that did not show the parallel orientations that clearly identify schist, although this may well have been their source.
The feldspars were often slightly weathered. In many cases the orthoclase was the bearer of microperthitic in- tergrowth. The plagioclase was often twinned with re- spect to the albite or Carlsbad laws. The identification of the cordierite required particular care owing to its similarity to quartz and feldspar under the microscope.
Both the chlorite and the amphibole(?) were strongly pleochroic, the colors ranging from yellow to pale green in the former and brown to dark green in the latter. The yellow and brown color of minerals is frequently pro- duced or enhanced through the effects of firing. The
222 Punic Amphoras at Corinth: Origin and TechnologylManiatis et al.
cially, Dr. G. Dontas, Inspector General of Antiquities in 1979, for granting those permissions that were needed in order that the present researches could be conducted.
Y. Maniatis, A. Kostikas, and A. Simopoulos, members of the Physics Department at N.R . C. Demokritos, have been engaged for many years in research into the physical properties of clays and their relationship to archaeological ceramics using Mossbauer spectroscopy and scanning electron microscopy.
R. E. Jones has been director of the Fitch Laboratory since 1974.
I. K. Whitbread is working in collaboration with the Corinth Excavations, making a petrological study principally of Corinthian amphora fabrics. He is currently in the Department of Archaeology at Southampton University.
Ch. Karakalos directs the X-ray radiography unit at N.R.C. Demokritos.
C. K. Williams, II, has been the director of the Corinth Excavations since 1967.
stronger body color then tends to mask the interference colors. In many cases the chlorite had become cloudy because of alteration, possibly as a result of firing. The pyroxenes were present only in very small quantities and consequently their identification can only be regarded as tentative until many more samples have been analyzed.
Lime refers to the minute crystals of calcium minerals that were scattered throughout the matrix of most of the fabrics and often lined the rims of voids.
2. Discussion of the Rock Fragments and the Sources of the Temper
The rock fragments point towards sedimentary and metamorphic sources for the temper. The metamorphic fragments consisted of biotite and muscovite schist and amphibole(?) schist. In one fragment of schist, biotite, chlorite, and amphibole were all present, while in an- other garnet and muscovite were both present. Chlorite and plagioclase formed one type of rock fragment found in subgroup (e), while white mica, quartz, and kyanite formed another. Subgroups (d) and (e) were the richest in serpentinite (usually brown from the effects of firing). With respect to the metamorphic rocks it is the coexis- tence of mineral phases in equilibrium (a mineral para- genesis) that defines the metamorphic grade and environment. As Winkler44 points out, however, the pre- cise relationships between mineral phases must be estab- lished before interpretation based on parageneses can be made. Consequently, the attribution of the metamorphic material to a particular grade and environment depends solely upon the interpretation of the rock fragments whenever these are available. The assemblages described above appear to belong to environments ranging between low- and high-grade regional metamorphism.45 In gen- eral, the metamorphic inclusions in the sedimentary fab- rics belong to the low grade, although rare intrusive examples of the higher grades do occur. The reasons for the mixing of low-grade (chlorite) and medium- to high- grade material (kyanite, sillimanite) cannot be explained without detailed knowledge of the geology of the source region. It is possible that it occurred during transport of weathered rock fragments by natural agencies.
Acknowledgments
It is with great pleasure that we are able to thank the Greek Archaeological Service, the Archaeological Ephoreia of the Argolid and the Corinthia and, espe-
44. H. G. F. Winkler, Petrogenesis of Metamorphic Rocks (Springer Verlag: New York 1979) 28.
45. F. J. Turner and J. Verhoogen, Igneous and Metamorphic Petrol- ogy (McGraw Hill: New York 1960) 531-560.
