Marino Maggetti

The emergence of pottery in Africa during the tenth millennium cal BC: new evidence from Ounjougou (Mali)

New excavations in ravines at Ounjougou in Mali have brought to light a lithic and ceramic assemblage that dates from before 9400 cal BC. The authors show that this first use of pottery coincides with a warm wet period in the Sahara. As in East Asia, where very early ceramics are also known, the pottery and small bifacial arrowheads were the components of a new subsistence strategy exploiting an ecology associated with abundant wild grasses. In Africa, however, the seeds were probably boiled (then as now) rather than made into bread.

Geomaterials in Cultural Heritage

This volume gives a broad view of the application of geoscience techniques to the study of monuments and objects from excavations and museums, including their origin, technique of manufacture, age and conservation. It reaffirms the important contribution of geosciences in the interdisciplinary approach to the study of complex materials such as minerals, rocks, glass, metals, mortar, plaster, slags and pottery. The papers in this book cover three topics: the study of pottery, glass, stone and mortar; the application of Raman spectroscopy to a wide variety of objects; and the future of archaeometry. Interdisciplinary studies including field geology, geophysics, microscopy, textural analysis, physical methods and geochemistry are used to unlock information from the ancient materials, such as the provenance of the raw materials, the firing technology, the ancient recipes, and the alteration pathways.

SAPONITE FROM THE EMET COLEMANITE MINES, KÜTAHYA, TURKEY

Clay mineralogy and whole-rock chemistry of the borate-bearing layers of the Hisarcik and Esbey mines were examined. The Hisarcik clays occur as laminated or unlaminated clay layers with sharp contacts. Unlaminated layers contain quartz derived from metamorphic rocks and carbonate fragments in a clay matrix, and are interpreted as reworked tuffs deposited in playa-lake environments. An important feature is that the unlaminated clays contain little MgO (3–15 wt. %) as compared with the laminated clays (15–30 wt. %). As previous studies have shown, the clay fraction of the studied profile contains predominantly Li-bearing saponite, and accounts for 60–90 wt. % of the clay fraction (<2 μm). Illite in the clay fraction varies from 0 to 67 wt. % and the average illite percentage never exceeds 40 wt. %. Chlorite is scarce (2–5 wt. %). Illite-smectite interstratified clays (illite at 70%, smectite at 30%) were only found in low concentrations in the laminated clay layers of the upper limestone unit (above the borate zone), where illite-2M of detrital origin is also present. The Esbey clays occur interstratified with colemanite layers and envelope colemanite nodules. Calcite is the major mineral of the clays whereas quartz, plagioclase, feldspar, colemanite, and cahnite are minor components. The MgO contents vary between 4.70–13.95 wt. % in the clays interstratified with colemanite layers, between 7.24–11.89 wt. % in the enveloping clays, and between 10.27–21.25 wt. % in clays located above the colemanite zone. The composition of the clay fraction (<2 μm) in all samples is similar. Smectite represents between 40–90 wt. % of the clay fraction in the upper portion of the stratigraphic profile and decreases towards the lower part of the stratigraphic profile. Smectite always occurs with illite which may vary from 20 to 90 wt. % of the clay fraction, and a small amount of kaolinite and chlorite. Illite-2M polytype is abundant. The d(060)-reflection position suggests that the smectite minerals from the Hisarcik and Esbey colemanite mines contain both dioctahedral and trioctahedral smectites to form a transitional zone. These smectites are a product of a magnesium-rich alkaline playa-lake environment.

Evolution of the Silvretta Nappe

The Silvretta basement nappe had a complex Precambrian and Palaeozoic history. During the Proterozoic, sedimentation of mostly greywackes occurred in a back-arc situation, probably contemporaneously with voluminous intrusions/extrusions of MOR basaltic magmas. A first metamorphic overprint in amphibolite facies conditions preceded a high pressure event (“eclogitic” peak conditions 550–650 °C, min. 14–16 kb). In Late Proterozoic time, intrusions of basic to intermediate magmas (older orthogneisses) occurred. A Rb-Sr isochron of 895 + 130/−140 Ma is interpreted as crystallization age. The geochemical composition indicates, as for the eclogitic event, a collisional regime for the generation of these magmas. A second HP event occurred before the intrusion/extrusion of acid magmas (younger orthogneisses). Their Rb-Sr isochron of 451 ± 2 Ma is interpreted as an Ordovician crystallization age. This magmatism occurred probably during an Early Palaeozoic continental rifting causing their generation and emplacement. The Variscan deformation and metamorphism was a polyphasic amphibolite facies event. The metamorphic peak (600–650 °C, 5.5–7.5 kb) was dated with Rb-Sr small scale isochron at 370 ± 17 Ma. An uplift caused the crystallization of andalusite in the rocks and in veins. The following compressional event (assumed 450–550 °C, ~4 kb) led to the formation of kilometre-long folds. Rapid rise of the Silvretta crystalline complex and extensional tectonics in the Pangea resulted in the intrusion of Late Carboniferous (310–280 Ma?) rift tholeiites, which are preserved as dykes. Continuous extensional tectonics resulted in the formation of horst and graben structures, filled with Permian acid volcanic detritic material and ignimbritic flows. The Silvretta nappe then began to subside and terrigeneous material as well as dolomites were deposited in Triassic-Jurassic time. The Alpine metamorphism (110–90 Ma) reached anchizonal facies conditions in the west and greenschist facies conditions in the east of the Silvretta. Then the Silvretta was uplifted differentially and detached from the basement. Pseudotachylites (~75 Ma old) formed at this time and document fossil hypocentres of earthquakes. The overthrust of the Silvretta nappe onto the Pennine foreland occurred about 60–55 Ma ago.

Eclogites from the Silvretta nappe (Switzerland): Geochemical constraints on the nature and geotectonic setting of their protoliths

Abstract In the Austroalpine Silvretta nappe of central Europe eclogitic rocks of presumed Paleozoic metamorphic age have recently been found. Their chemical composition suggests that they were derived from evolved tholeiitic magmas which have undergone variable degrees of fractionation at shallow depths involving crystallization of plagioclase plus olivine and/or pyroxene. The igneous protoliths probably originated at a constructive plate margin. Although some chemical features closely resemble those of mid-ocean ridge basalts the composition of the metasedimentary country rocks suggests a tectonic setting close to a continental block, perhaps in a back-arc basin situation or incipient oceanic ridge.

Technological aspects of an early 19th c. English and French white earthenware assemblage from Bern (Switzerland)

Ceramic material from the Brunngasshalde town-waste-dump of Berne, the capital of Switzerland (infilling 1787 - 1832) encompasses 9.2 % white earthenware. Only 1 % of the latter bear impressed stamps of English, French and Swiss manufactures. All stamped English (WEDGWOOD, n=3) and French (CREIL, n=2; NIDERVILLER n=1) material was analyzed by XRF, XRD, MEB-BSE and MEB-EDS. The Wedgwood pottery is rich in coarse SiO 2 grains, interpreted as crushed flint fragments, with abundant signs of a high temperature treatment. They lay in a finely grained siliceous-aluminous matrix, in one specimen together with grog. The Creil material is very similar, but lacks grog. The English white earthenware has lower SiO 2 (73-76 wt. %) as Creil (77-79 wt. %), similar Al 2 O 3 (18-22 wt. %), but more K 2 O (ca. 1 vs. 0.4 wt. %) and Ba (200-220 ppm vs. 130 ppm). In comparison, previously analyzed early French white earthenware from Paris (n=5), produced in Pont-aux-Choux (c. 1750-1788), bearing the characteristic rice grain decoration, differs clearly in its concentrations of SiO 2 (60-61 wt. %) and Al 2 O 3 (32-34 wt. %). Creil and Wedgwood sherds must be classified as siliceous-aluminous white earthenware. The CaO-rich (17 wt.%) Niderviller fragment pertains to the calcareous white earthenware group. A comparison with 19 already published calcareous bodies from Lorraine shows similarities (crushed SiO 2 grains and lead frit as temper in a fine grained siliceous aluminous matrix), but its chemical composition differs from the published analysis of an object stylistically attributed to Niderviller. White earthenware glazes from Niderviller, Paris and the Wegdwood manufacture are transparent lead alkali glazes, and from Creil lead glazes. Niderviller has a K 2 O rich (5 wt. %) and Wedgwood an Al 2 O 3 rich (5-8 wt. %) glaze. Chemical elements diffused from the body to the glaze (e. g. lead) and conversely (e. g. alumina). All samples are artificial bodies, made from a white-firing clay, to which were added ground flint, calcined or not, with or without grog, or ground flint/quartz sand, calcined or not, and lead frits and chalk for the calcareous white earthenware. These results are in good accordance with old recipes. They are also the first archaeometric study of undoubtly (trademark!) Creil, Niderviller and Wedgwood tableware.

Contrasting recipes for the kiln furnitures of the faience manufacture Granges-le-Bourg (Haute Saône, France)

Thirty-nine samples of kiln furniture or technical ceramic (firing plate, saggars, spacers, props, wads) and six samples of building ceramics (bricks, tiles) from the manufacture of Granges-le-Bourg were studied by optical microscopy, X-ray fluorescence, X-ray diffraction and scanning electron microscopy. The kiln furniture is chemically inhomogeneous and belong to a CaO+ MgO-poor (firing plate, saggars) or a CaO+ MgO-rich (props, spacers, wads) group. Bricks and tiles pertain to the first group, which was manufactured using decarbonatized top layers of local Triassic dolomitic marls. For the second group, the deeper layers were used. Plate and saggars are covered with a tin oxide opacified glassy coating with no significant reaction zone to the body.

Archaeometry: quo vadis?

Abstract First, a brief overview of the tasks and the historical development of archaeometry will be given. Although archaeometry is generally doing well, a few issues currently faced by this discipline will be outlined. These include: (1) funding for projects and research positions; (2) the appeal of archaeometry to a new generation of academics; (3) the standard of publications; (4) the safeguarding of and the immediate access to scientific data.

Paul-Louis Cyfflé’s (1724–1806) search for porcelain

Seven unglazed figurines from private collections, attributed to Cyffle’s Terre de Lorraine manufacture in Luneville (1766–1780), were subjected to porosity and scanning electron microscopic analyses to determine bulk element compositions and the composition and nature of their constituent phases. One figurine bears the mark CYFFLE A. LUNEVILLE, three the mark TERRE DE LORRAINE. The studied samples pertain to four compositional groupings: (1) Two porous (18–20 % water adsorption W.A.) bodies containing milled quartz-rich frit +anhydrite (former gypsum) +phyllosilicate +Ca-rich matrix; (2) A soft-paste (artificial) porcelain body (10 % W. A.), containing quartz +calcic plagioclase (An 88–95 ) + glassy matrix. The latter is inferred to derive from a former frit. A coronitic, amorphous (as revealed by electron backscattered diffraction analysis) reaction rim is visible around the quartzes. The K-rich and Na-poor composition of the frit is best explained as a mixture of potassium nitrate, alum, calcined gypsum, sand, and moderate amounts of salt and soda; (3) A porous (23 % W. A.), hybrid porcelain body with finely milled particles of quartz, mullite-bearing hard-paste porcelain, Na-Ca-siliceous glass and metakaolinite; (4) Three hard-paste porcelain bodies, some with relict quartz, andesine plagioclase (An 37–45 ), pseudomorphs of kaolinite and the liquidus phase mullite in a glassy matrix. Well fired figurines have no W. A. due to the pervasive former melt phase, underfired figurines 7 %. These wares can contain small amounts of lead (1.8 wt% PbO) and SO 3 (0.6 wt%), suggesting the use of lead frit and gypsum. The diversity of Cyffle’s production is now better recognized. His trial-and-error experiments made use of a remarkably wide range of paste mixtures, with porcelain bodies in the French (soft-paste) and the German (hard-paste) tradition.

Französische und schweizerische Fayencen zwischen Mythos und Realität

Majolika, Fayence und Delfter Ware sind Synonyma fur eine ganz spezielle Keramikgattung. Es handelt sich dabei um eine Irdenware, die auserlich wie Porzellan aussieht. Zu diesem Zwecke wird der bleihaltigen Glasur Zinnoxid (SnO2, Cassiterit) als Trubungsmittel zugesetzt. Die Gefase erscheinen so weis. Diese Topferresp. Glasurtechnik ist ca. 1000 Jahre alt und wurde im 9. Jh. n. Chr. im mesopotamischen Raum eingefuhrt. Auf Grund des porzellanartigen Aussehens in Form und Dekor der altesten Fayencen dieses Gebietes ist anzunehmen, dass der Zinnzusatz nicht zufallig, sondern absichtlich erfolgte, wahrscheinlich um die zu dieser Zeit nach Mesopotamien gelangenden ersten chinesischen Porzellangefase der T’ang Dynastie zu imitieren (Caiger-Smith 1973). Im Laufe der Eroberungen des Mittelmeerraumes durch die Araber gelangte die neue, musulmanische Glasurtechnik auch nach Spanien. Im 12.–15. Jh. war sie dort in Zentren wie Talavera-Puente, Paterna-Manises und Sevilla in hoher Blute. Von Spanien kam der Keramiktyp nach Frankreich — Mitte des 13.Jh. wurde in Marseille Fayence produziert (Marchesi et al. 1997) — und uber die Balearen nach Italien, z.B. Faenza, und von dort verbreitete sich die Kenntnis der Fayenceproduktion nach Norden und Westen weiter. So entstanden laufend weitere Manufakturen in Frankreich, Deutschland, Holland, England, der Schweiz usw.