Schlagwort-Archive: Nubian style

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

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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

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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.

Thinking about style in colonial Nubia

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I have thought a lot about style recently ‒ on the one hand about stylistic questions of Ptolemaic coffins for the Ankh-Hor project, as well as for class preparation about Egyptian art, but of course also during the processing of ceramics from Nubia, from the colonial town of Sai Island.

Style is in general a much-disputed label in archaeology and art history. Recent studies have introduced a focus on “style as effect” (Bussels and van Oostveldt 2020, 221 with references), stressing the transformative power of style and discussing style together with objects and agency. Stylistic variations as reflections of intercultural exchange seem to be very evident in the ceramic corpus from colonial Nubia during the New Kingdom.

It is well established that are clear differences regarding the Egyptian style and the Nubian style pottery corpora in colonial Nubia, not only in terms of shape but also regarding the technology with wheel-made Egyptian and hand-made Nubian vessels. From the beginning of my study of pottery from Sai Island, I used the term “Egyptian style” for wheel-made products and soon differentiated between locally produced variants and imported vessels.

But let’s come back to the broad concept of style – I believe the main aim should be to address the complex processes involved in producing objects (as proposed by Marian Feldman 2006 for the “International Style” of the Late Bronze Age). My labels for New Kingdom pottery in Nubia also stress the production process – vessels which appear within the Nubian respectively in the Egyptian tradition, without marking them already as Nubian or Egyptian production. Of interest is the effect and the role these objects took in the framework of cultural encounters – sometimes taking hybrid forms, making it impossible to separate the distinctive traditions from each other. Hybrid pottery products from colonial Nubia must be regarded as something new and separating Egyptian and Nubian elements on these pots is not helpful or applicable. Giulia D’Ercole is currently working within the DiverseNile project on these hybrid products and their significance for cultural encounters, focusing on the production technique including the raw materials.

Within New Kingdom Nubia, regional style in ceramics was mostly expressed by surface treatment and decoration (see already Miélle 2014). One exceptional case is that the colonial experiences on Sai resulted in a new style of painting wheel-made ceramics. Deep bowls are attested in all sectors of the town and find parallels in Askut. Stuart Tyson Smith interpreted the preference of wavy lines and painted triangles on these bowls as local Nubian style (Smith 2003, fig. 3.7). Laurianne Miellé concentrated on the pending triangles painted in black on red and which seemingly refer to earlier Nubian decoration patterns known from C-Group vessels and Kerma Moyen bowls (Miélle 2014, 387‒389, fig. 4). However, this is not simply an inspiration by means of motif but there was a striking transformation in the execution style – incised decoration was carried out as painted decoration. Here, the colouring scheme seems to have been influenced by the new black-on-red style which became fashionable in the early 18th Dynasty, both in Egypt and New Kingdom Nubia. The shapes are markedly different from any Nubian style vessels and typically Egyptian; the production technique is also Egyptian, but in local variants of Nile clays. All in all, this new style of painted vessels must be seen as the embodiment of colonial experiences, transforming different cultural traditions to something new with multiple affinities in both directions.

Typical New Kingdom pottery context from the colonial town of Sai (photo J. Budka, processing S. Neumann).

Just as one example, this mixed context of sherds from sector SAV1 West in the colonial town of Sai shows the multiple styles of pottery we typically encounter in this urban centre with a strong cultural diversity in its material culture. There are imported Marl clay vessels from Egypt, one of which is painted and could be labelled as „Levantine style“ (although an Egyptian product); there are two bichrome decorated Nile clay vessels which were maybe produced locally in Nubia, but are very similar in style to Marl clay vessels and Nile clay vessels known from Egypt (see Budka 2015); one example attests the wheel-made painted bowls which seem to express a very specific colonial Nubian style restricted to Nubia (but here the style of painting is less clearly inspired by Nubian incised decoration). And finally, there is an undecorated, wheel-made dish produced locally on Sai and the rim sherd of a Kerma Classique beaker, probably also manufactured locally (and not imported from the Third Cataract region).

Sai is clearly another case study for a distinctive “local variation within a generally shared repertoire of material culture” (Näser 2017, 566) commonly found in New Kingdom Nubia which originates from specific social practices (Lemos 2020). Within the DiverseNile project and with our contact space biography approach, also considering the concept of Objectscapes, I believe we can take the results from Sai further. One aspect I will be working on in the next weeks is whether the intriguing concept of “Communities of Style” (Feldman 2014) is applicable to questions about pottery production in colonial Nubia, first of all for Sai and its hinterland, the MUAFS concession area.

References:

Bussels and van Oostveldt 2020 = Stijn Bussels and Bram van Oostveldt, Egypt and/as style, in: Miguel John Versluys (ed.), Beyond Egyptomania: objects, style and agency, Berlin/Boston, 219–224.

Budka 2015 = Julia Budka, Bichrome Painted Nile Clay Vessels from Sai Island (Sudan), Bulletin de la céramique égyptienne 25, 331–341.

Feldman 2006 = Marian Feldman, Diplomacy by Design. Luxury Arts and an ‚International Style‘ in the Ancient Near East,1400-1200 BCE, Chicago.

Feldman 2014 = Marian Feldman, Communities of Style : Portable Luxury Arts, Identity, and Collective Memory in the Iron Age Levant, Chicago.

Lemos 2020 = Rennan Lemos, Material Culture and Colonization in Ancient Nubia: Evidence from the New Kingdom Cemeteries, in: Claire Smith (ed.), Encyclopedia of Global Archaeology, Cham, https://doi.org/10.1007/978-3-319-51726-1_3307-1.

Miélle 2014 = Laurianne Miélle, Nubian traditions on the ceramics found in the pharaonic town on Sai Island, in: Julie R. Anderson and Derek A. Welsby (eds.), The Fourth Cataract and Beyond. Proceedings of the 12th International Conference for Nubian Studies, British Museum Publications on Egypt and Sudan 1, Leuven, 387–392.

Näser 2017 = Claudia Näser, Structures and realities of the Egyptian presence in Lower Nubia from the Middle Kingdom to the New Kingdom: The Egyptian cemetery S/SA at Aniba, in: Neal Spencer, Anna Stevens and Michaela Binder (eds.), Nubia in the New Kingdom. Lived experience, pharaonic control and indigenous traditions, British Museum Publications on Egypt and Sudan 3, Leuven, 557‒574.

Smith 2003 = Stuart Tyson Smith, Pots and politics: Ceramics from Askut and Egyptian colonialism during the Middle through New Kingdoms, in: Carol A. Redmount and Cathleen A. Keller (eds.), Egyptian Pottery. Proceedings of the 1990 Pottery Symposium at the University of California, University of California Publications in Egyptian Archaeology 8, Berkeley, 43–79.

Update on Raman Spectroscopy analysis on Nubian and Egyptian style samples

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At the beginning of June, we have announced the launch of a new pilot study – as part of the WP 3 of the DiverseNile project – implementing and testing the potential of the Raman Spectroscopy technique on a selection of ceramic samples coming from our reference collection from the sites of Sai Island (SAV/S-samples) and Dukki Gel, Kerma (DG-samples).

This study is currently in progress as part of our cooperation with the Department of Earth and Environmental Sciences of the LMU, and namely with Fabian Dellefant, co-author of this post, who is a geoscientist and doctoral student under the supervisors of Prof. Dr. Trepmann and Prof. Dr. Gilder.

Due to fast measurements and its non-destructive approach with only little sample preparation, Raman spectroscopy can be easily applied to ancient ceramic materials, answering various technological questions, in particular on the manufacturing stages of production and firing of the pots.

For our investigation, we analysed so far a total number of 8 samples/thin sections (namely samples DG-18, DG-23, DG-29, DG-35, SAV/S 02, SAV/S 14, SAV/S 17, and SAV/S 51). Of all these, micro photos were primarily taken under the petrographic microscope with both transmitted and reflected light in order to select the areas of the sample to be examined with Raman Spectroscopy (normally two different spots including the clay matrix and particular organic components, both within the inner portion or core of the sample and on the rim area).

These samples are either locally produced cooking pots or other local ware manufactured both according to the so-called Nubian (DG-18, DG-23, DG-29, and SAV/S 02) and Egyptian style (DG-35, SAV/S 14, SAV/S 17, and SAV/S 51).  All of them consist of a non-calcareous optically active clay matrix with dark cores and red or buff oxidised surfaces. In some specimens, the oxidised margins are narrow and well defined, while in others the red-black zonation appears larger and less regular. The Egyptian style samples normally show a kind of “sandwich” structure consisting of a dark core enclosed, both above and below, by red oxidised surfaces (Fig. 1).

Fig. 1 Photos of the fractures from thin section scanning of samples SAV/S 02 (left) and SAV/S 17 (right). Note the large amount of organic inclusions which have been totally or partially carbonized and are surrounded by voids. Both samples show a dark core due to insufficient penetration of oxygen during firing.

All these samples contain, in a different extent, organic matter either plant remains (chaff, straw, grass and possibly various cereals components), and probably herbivore manure (those finely divided straw particles). The organics are either totally or partially carbonized so that the plant inclusions are often preserved as black carbonized relics into the voids.

The carbonaceous core (dark-grey zone in the center of the ceramic samples) can be the result of insufficient firing under oxidizing conditions. It is also related to the use of a paste of high organic component. During the firing of the pot, the combustion of the organics acts indeed as a reducing agent, taking away oxygen from the firing environment (Velde and Druc 1999: 126-127, see also Quinn 2013).

In organic chemistry, the process of thermal decomposition, obtained by the application of heat and in the complete absence of an oxidizing agent is known as pyrolysis or graphitization.

Pyrolysis-GC/MS to ceramics which are conspicuously black or exhibit a black inner core from incomplete burn-out has been applied for the assessment of molecular properties of organic matter in archaeological pottery matrix (see Kaal et al. 2013).

In Raman Spectroscopy, vibrational modes of specific crystallographic components are used to determine a specific crystallographic structure. In our case, the temperature-dependent formation of graphite is used to quantify the highest temperature the sample has experienced.

The lab setup consists of an optical microscope with different magnifications and a computer software, which handles data acquisition (Fig. 2). Measurements are conducted by using a laser with a 532 cm-1 wavelength directly on the thin section which has been first well-polished and cleaned with ethanol. In the lab, temperature is kept constant at 18° C degrees with the lights turned off so as not to interfere with the measurement.

Fig. 2 Lab of the Museum Mineralogia in Munich with the optical microscope (right) and the computer (left), which were used for the investigation.

In the investigated ceramics, the precursor of the measured graphite can be either organic material, such as grass and straw, or dung of herbivores, which was mingled into the clay before heating. Furthermore, in some samples firing ash could have been added as well. Our preliminary results show that graphite can be clearly detected in the sample material. Interestingly, a group of samples showed graphite formation only within the organic components, which is interpreted as being the relicts from plant inclusions. Other samples clearly show graphite spectra also within the clay matrix, which could have been added to the clay as ash in the first place (see e.g., SAV/S 02, Fig. 3).

Fig. 3 Optical microphotograph with reflected light of sample SAV/S 02. Datapoint 12 (pink) marks an organic component in a void and refers to the Raman spectra SAV_2_1-r12 in Fig. 4. Datapoint 22 (blue) characterizes the ceramics matrix and refers to the Raman spectra SAV_2_1-r22 in Fig. 4.
Fig. 4 Raman spectra of a datapoint from the matrix and an organic component. The spectrum of the matrix refers to datapoint 22 and the spectrum of the organic component refers to datapoint 12 of Fig. 3.

The interpretation of the maximum temperature the sample experienced is based on the ratio of two Raman peaks, which have a wavenumber of ~1390 cm-1 and 1606 cm-1. Given the dataset shown in Fig. 4, the maximum temperature can be estimated to ~600 °C after Guizani et al. 2017.

In the following weeks, we will proceed to the data processing and potential grouping based on the various Raman spectra collected from our pottery samples (we measured on average up to 20-25 datapoints for each sample). This will allow us to develop our preliminary interpretations and come to more specific conclusions on the quality of the organic material added to the paste and the heating temperatures reached during the firing. Eventually we might get insights on the type of clay sources selected to make the pots.

We can maybe spoil a bit things for you, anticipating that possibly some of the examined samples experienced a more homogeneous firing than others, these latter showing otherwise varying temperatures!

References

Guizani, C., Haddad, K., Limousy, L., and Jeguirim, M. 2017. New insights on the structural evolution of biomass char upon pyrolysis as revealed by the Raman spectroscopy and elemental analysis. Carbon 119:519–521. http://dx.doi.org/10.1016/j.carbon.2017.04.078.

Kaal, J., Lantes-Suárez, O., Martínez Cortizas, A., Prieto, B., and Prieto Martínez, M. P. 2013. How Useful is Pyrolysis-GC/MS for the Assessment of Molecular Properties of Organic Matter in Archaeological Pottery Matrix? An Exploratory Case Study from North-West Spain. Archaeometry 56 (S1): 187–207. https://doi.org/10.1111/arcm.12057.

Quinn, Patrick S. 2013 Ceramic Petrography. The Interpretation of Archaeological Pottery and Related Artefacts in Thin Section, Oxford.

Velde, Bruce and Druc, Isabelle C. 1999. Archaeological Ceramic Material. Origin and Utilization, Berlin.