Schlagwort-Archive: Nubian pottery

Performing XRD analysis on Nile clay Nubian- and Egyptian-style samples from Attab and Ginis

Veröffentlicht am von
Antworten

Exams never end, not just for humans but even for archaeological artifacts.

Already before the Christmas break, I had happily returned to the lab, this time to prepare a new bunch of ceramic samples to undergo X-ray powder diffraction (XRPD) analysis. Thanks to a new cooperation with the TU München, and especially with Prof. H. A. Gilg (Chair of Engineering Geology) we decided in fact to complement our iNAA and OM analyses with this new laboratory methodology, with the aim of expanding our knowledge on the composition, provenance and technology of production of our Nile clay samples. All in all, we preliminary selected 30 ceramic specimens, among Nubian- and Egyptian-style sherds from the 2022 and 2023 excavated sites at Attab West and Ginis East. To this sample, we added a replica in modern Nubian (from Abri) Nile clay manufactured by us during our last workshop in Asparn.

Generally speaking, X-ray powder diffraction analysis is a well consolidated analytical technique used in the field of archaeometry and ceramic technology to determine the mineral phases present in the pastes, including those clay phases which are typically not visible under the microscope. This technique also provides information on the firing process the pottery went through. Certain minerals (e.g., calcite as one of the most known) can in fact degrade, disappear or be altered at given temperatures because the crystalline structure collapses through the process of dehydroxylation (Magetti 1982; Rice 1987). The analysis itself based on the phenomenon of diffraction of electromagnetic radiation, by exploiting the fact that X-rays falling on crystalline planes in minerals are reflected at varying angles (Velde and Druc 1999; Quin 2013). Hence, each mineral type will produce a characteristic X-ray diffraction spectrum with diagnostic peaks placed at given angular distances (expressed in degrees 2θ), allowing the qualitative identification of the minerals present within the ceramic sample. The heigh of those picks permits otherwise a semi-quantitative estimation of the ratios in which minerals are more or less represented.

Figure 1 – Lab kit for the preparation of samples for XRD analysis. Photo by G. D’Ercole.

Sample preparation is pretty much straightforward although partially destructive. The procedure requires that a tiny portion of the sherd be ground up (about 1g of powder) by hands with an agate mortar and a pestle, alike those used for iNAA, pressed in the mounting smear slide, and then put into the instrument. Proper pulverization and homogenization are crucial to achieve highly quality XRD data.

Figure 2 – Pulverization of the sample by hands in the agate mortar. Photo by G. D’Ercole.

The sample needs to be as representative of the ceramic sherd as possible – for this reason, it is sometimes advisable to grind a larger quantity of powder and above all finely ground so as to prevent larger crystals (e.g., coarse quartz grains) from interfering with the measurement. This latter can be carried out with different timing and levels of accuracy depending on whether one wants only a rough semi-quantitative estimate of the mineral phases in the sample or more accurate information.

Figure 3 – First set of potsherds ground up and ready to be analysed by XRD analysis. Note the diverse powder colours from black (reduced fired Nubian samples) to reddish-brown (oxidized fired Egyptian sherds). Photo by G. D’Ercole.
Figure 4 – Samples ready in the mounting smear slides. Photo by G. D’Ercole.

In performing XRD analysis, our main archaeological questions were the following:

  • Can we recognize the use of different clay raw materials for the different sites/locations (e.g., Attab, Ginis…);
  • Can we differentiate between Nubian- (also Pan-Grave) vs. Egyptian-style samples;
  • Can we differentiate between the different ceramic types and wares;
  • Can we demonstrate the intentional addition of tempers (calcite and/or quartz and/or feldspar and/or mica) in particular samples?
  • Can we know more about the firing process (i.e., firing temperatures) the ceramics went through?

Currently, together with Prof. Gilg, we just started to interpret the results of the first diffractograms. The data are not always straightforward to read and the differences between the various samples look sometimes very subtle – on the other hand our Nile clay samples have used us to significant challenges for many years already!

Preliminary, we can say that, based on the diagnostic mineral phases in the various spectra, it was possible to recognise four distinct groups or types of samples. These groups do not depend on the main phases (quartz or feldspar) as these are present in nearly homogenous amounts in all samples. Rather, some differences can be spotted in the clay minerals. Whether these latter can be ascribed to different clay sources, preparation recipes, or eventually the pot production (i.e., firing) has yet to be fully assessed.

References

Maggetti, M. 1982. Phase Analysis and its Significance for Technology and Origin. In J. S. Olin and A. D. Franklin (eds.), Archaeological Ceramics: 121−133. Washington, Smithsonian Institution Press.

Quinn, P. S. 2013. Ceramic Petrography: The Interpretation of Archaeological Pottery & Related Artefacts in Thin Section. Oxford, Archaeopress.

Rice, P. M. 1987. Pottery analysis. A sourcebook. Chicago, University of Chicago Press.

Velde, B. and Druc, I. C. 1999. Archaeological Ceramic Material. Origin and Utilization. Berlin Heidelberg, Springer-Verlag.

From the field to our office in Munich: the voyage of a Nubian cooking pot

Veröffentlicht am von
Antworten

Excavations at the site AtW 001 on the west bank of Attab yielded a very large number of pottery sherds – I processed more than 10.300 pieces in our digging house in Ginis during the 2023 season and the final analysis and reconstruction of the number of individual vessels is still ongoing. Already in the field it became clear that a surprisingly large number of intact vessels has survived. These included primarily dishes and plates, beer jars, zir vessels, pot stands and cooking vessels – thus a clearly domestic set of ceramics which finds many parallels in the corpus I processed from the temple town of Sai, but also shows unique and specific features – just fantastiic material which allows addressing a number of various research questions!

Our sherd yard in the digging house was almost getting to small because of the large amounts of sherds from AtW 001!

One particular interesting piece which I would like to present today is a large fragment of a typical Nubian style cooking pot. The complete profile of this pot is preserved and it was found in dense mud brick debris, half buried below a collapsed brick. This context yielded a total of 34 pottery sherds with 15 diagnostic pieces and several almost complete vessels; the total of Nubian wares accounted to 32%, nicely confirming our results from 2022 when the number of Nubian wares in the various fill horizons was high, accounting for on average 33% of the ceramics (Budka 2022).

Overview of context SU 1257 with the large Nubian cooking pot below the mud brick where I placed the scale.

The Nubian pot in question is an example of the most common type of Nubian globular bowls used as cooking pots we found at AtW 001. The vessel shows plaited basketry impression with large rectangular patterns and a distinct rim zone. Such vessels find close parallels at Sai, Sesebi and other New Kingdom sites in Nubia (e.g. Rose 2012; Budka 2020). These basketry impressed cooking pots are firmly rooted in a Kerma tradition of shaping pots in a concave hole using mats/baskets but show an intriguing change of technique in the early 18th Dynasty which is present at sites between the Dongola Reach and southern Upper Egypt (see Gratien 2000 for the new style of basketry impressions starting with so-called Recent Kerma).

Our complete example from AtW 001 started its long journey on Jan. 30 which is not yet over – from the field to the digging house where it was washed, photographed and then put on my drawing table. The pencil drawing I created in Sudan is now in the process of being digitalised – Caroline scanned the drawing already and started the final digital drawing for publication on our interactive multi-touch pen display in the office.

Caroline already started digitalising the original pencil drawing of the Nubian cooking pot.

Apart from this, we took two samples from this Nubian cooking pot. One of which will be analysed using Instrumental Neutron Activation Analysis – here, we aim to get information about the provenience of its fabric since this pot clearly seems to be a local product. The second sample is waiting for Organic Residue Analysis, hopefully enabling us to reconstruct what was once cooked within this pot. More details about our approach combining standard macroscopic analysis of pottery with various complementary laboratory methodologies can be found in an earlier blog post by Giulia D’Ercole.

As I hopefully could illustrate, the complex voyage of this Nubian cooking pot will continue – but within just 2 months we have already achieved important working steps in order to publish this important fragment of evidence of settlement activity on the west bank of Attab during the early New Kingdom.

References

Budka 2020 = Budka, J. AcrossBorders 2. Living in New Kingdom Sai. Archaeology of Egypt, Sudan and the Levant 1. Vienna: Austrian Academy of Sciences Press, 2020.

Budka 2022 = Budka, J. Early New Kingdom settlement activities in the periphery of Sai Island: towards a contextualisation of fresh evidence from Attab West, MittSAG – Der Antike Sudan 33, 2022, 45‒61.

Gratien 2000 = Gratien, B. Les pots de cuisson nubiens et les bols décorés de la première moitié du 2e millénaire avant J.-C.: problèmes d’identification, Cahiers de la céramique égyptienne 6, 2000, 113‒148.

Rose 2012 = Rose, P. Early 18th Dynasty Nubian Pottery from the Site of Sesebi, Sudan. In Nubian Pottery from Egyptian Cultural Contexts of the Middle and Early New Kingdom. Proceedings of a Workshop held at the Austrian Archaeological Institute at Cairo, 1–12 December 2010. Ergänzungshefte zu den Jahresheften des Österreichischen Archäologischen Institutes 13, ed. by I. Forstner-Müller and P.J. Rose, 13‒29. Vienna: Österreichisches Archäologisches Institut, 2012.

First preliminary remarks on the petrography of the Dukki Gel ceramic samples

Veröffentlicht am von
Antworten

In the last few weeks I haven’t been very present in our blog since I spent much time sitting at the microscope of the Department of Earth and Environmental Sciences of the LMU, just nearby to our office, examining and documenting the first batch of ceramic samples from the site of Dukki Gel. These samples have been included as a reference collection within our DiverseNile project thanks to the kind agreement of the excavator, Charles Bonnet, and the responsible ceramicist Philippe Ruffieux. Philippe has already studied all of these samples within their context and we can now address fresh questions within the DiverseNile work packages and with scientific analysis.

In times of the Covid pandemic, the procedure to access the laboratories is rightly strict: registration is mandatory before working in the microscopy room, only a maximum of three people are allowed to work simultaneously in the lab and of course we are required to wear medical masks and disinfect all devices and workspace at the end. All this will seem obvious, but what I personally find curious is the contrast between the meticulousness of the analytical procedure, further complicated by the current Covid rules, and the simple and tangible nature of the ancient ceramics, whose immense  anthropological and material complexity, and huge archaeological interpretative potential is all enclosed in a thin section of just 30 microns thick.

In my last blog post – I introduced the method I use for the classification of the ceramic samples and the layout within the Filemaker database which I specifically designed for the purpose of the petrographic study.

So far a total of twenty-one ceramic samples from Dukki Gel has been analysed by optical microscopy (OM), while forty-three samples are currently located at the Atominstitute in Vienna where they are being analysed for instrumental Neutron Activation Analysis (iNAA) by our colleague and external expert in the project Johannes Sterba.

Most of the samples for OM (18 out of 21) are Nubian vessels among which are cooking pots (both basketry impressed and incised ware), jars, globular vessels and also fine black topped Kerma ware. Further, three Egyptian-type vessels (two red slipped bowls and one fragment of a bread mould) were analysed under the microscope.

Petrographically, the Nubian samples from Dukki Gel appear quite homogeneous in term of their composition, displaying mineralogical and textural features which also resemble very much the petrography of the Nubian samples analysed from the New Kingdom town of Sai Island (see D’Ercole and Sterba 2018; D’Ercole in prep.). Differences in the textural features, in the proportion of some specific mineral phases, and in the amount and type of the organic tempers contained in the paste allowed distinguishing four principal petrographic groups or micro fabrics. The first group is characterized by a very sandy framework with a dominant grain size in the class of silt to very fine-grained sand, a good sorting of the non-plastics and very few organics mainly small and tubular in shape. The second group also displays a sandy framework, sorting is moderate with some medium sized rounded quartz and feldspar possibly added as temper, and common tubular organics partially carbonized and moderately aligned. Group 3, to which belongs the majority of the analysed samples, is sandy, moderately sorted, with common to abundant organics, either partially or completely carbonized, heterogeneous in shape and size,  and possibly referring to various parts of plant remains (including stem, glume, palea, and lemma?) (Fig. 1) and also herbivore dung. Finally, the fourth group of Dukki Gel Nubian samples contains abundant heterogeneous organics similar to group 3 but also large carbonate inclusions of microcrystalline calcite most likely intentionally added as tempering material. To this last group, which does not show a real comparison with the material from Sai, where the presence of calcite was ubiquitous and seemed a natural component in the clay source/ soil rather than a tempering agent, refers exclusively cooking pots with basketry impressions and a single jar.

Figure 1 – Detail of organic inclusion with visible plant cell structure from Sample DG-17. PPL micropho by G. D’Ercole.

All in all, similarly to what was observed for Sai Island, the petrofacies of the Nubian ceramics is very homogeneous and points to the selection of clays, or better soils, derived from local Holocene Nile alluvia, with a composition very similar along the various sectors of the Nile river (D’Ercole and Sterba 2018). These ceramics were possibly tempered with some medium- and coarse-sized aeolian sand or with quartz grains drained by the local river systems. Technologically, the amount and type of the organic material added to the paste (more or less abundant and selected) makes the main difference and allows distinguishing among various sub-recipes or ways of doing the vessels. Further, the orientation of the voids left by the combustion of the organic matter into the paste permits to recognize among the use of different manufacturing techniques. Specifically, in the cooking pots with basketry impressions which were built on a mat, the organics appear generally well or moderately aligned with a prevalent presence of longitudinal features like stems or plant stalks (Fig. 2a). Differently, in those pots (e.g., globular pots, bowls) built with the coiling technique, the organics show mainly a poor alignment and a specific orientation that indicates the ‘relict’ coil features (Fig. 2b). The black topped and the fine polished Kerma ware generally contain less organics, these latter are also smaller in size indicating either the use of herbivore dung and/or a selection of added plant remains.

Figure 2a – Thin section scan of Sample DG-18 (Nubian cooking pot). The good alignment of the pores structures and of the voids and relicts left by the combustion of the organics indicates that this vessel was built on a mat. Image by G. D’Ercole.
Figure 2b – Thin section scan of Sample DG-17 (Nubian large bowl). The specific concentric alignment of the pores structures and of the voids and relicts left by the combustion of the organics indicates that this vessel was manufactured with the coiling technique. Image by G. D’Ercole.

Highly interesting in the sample from Dukki Gel, is the presence of a jar with a roughly polished / wet-smoothed black surface which although showing clear Nubian technological exterior features is characterized by a coarser and sandier fabric with more abundant feldspar and granitoid rock fragments resembling certain Egyptian cooking pots (Fig. 3). This sample, so far an unicum in our selection, points to an hybridization of Nubian and Egyptian traditions (this time with the intersection of some performance of ‘Egyptian’ criteria to a general Nubian technological and stylistical formula) and well supports our overall theoretical framework and working approach on the complexity and diversity among various Nubian local narrative experiences and conceptions of material culture.

Figure 3 – Sample DG-22 (Nubian jar) with roughly polished / wet-smoothed surfaces characterized by a sandy fabric rich in alkali feldspar. Photo by G. D’Ercole.

Hopefully by the end of this month, we also will have the first set of chemical data from the reference collection from Dukki Gel in our hands which we will then compare with the macroscopic evidence and with these petrographic remarks.

References

D’Ercole, G. In prep. Petrography of the pottery from the New Kingdom town of Sai, in: J. Budka, with contributions by G. D’Ercole, J. Sterba and P. Ruffieux, AcrossBorders 3: Vessels for the home away from Egypt. The pottery corpus from the New Kingdom town of Sai Island. Archaeology of Egypt, Sudan and the Levant. Vienna.

D’Ercole, G. and Sterba, J. H. 2018. From macro wares to micro fabrics and INAA compositional groups: the Pottery Corpus of the New Kingdom town on Sai Island (northern Sudan), 171–183, in: J. Budka and J. Auenmüller (eds.), From Microcosm to Macrocosm: Individual households and cities in Ancient Egypt and Nubia. Leiden.