Century Majolica Pottery Found on the Canary Islands - American

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Downloaded by UNIV OF TEXAS EL PASO on November 8, 2014 | http://pubs.acs.org Publication Date: August 16, 2007 | doi: 10.1021/bk-2007-0968.ch021

Characterization of 15 -16 Century Majolica Pottery Found on the Canary Islands 1

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Javier Garcia Iñañez , Jaume Buxeda i Garrigós , Robert J. Speakman , Michael D. Glascock , and Elena Sosa Suárez 2

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ERAUB (Equip de Recerca Arqueomètrica de la Universitat de Barcelona), Dpt. Prehistòria, H.Antiga i Arqueologia, Facultat Geografia i Història, Universitat de Barcelona, c/ Montalegre, 6-8, 08001 Barcelona, Catalonia, Spain Research Reactor Center, University of Missouri, Columbia, M O 65211 Canarias Cultural y Arqueológica, S. L., Pancho Guerra, 22,3-B, 35014 Las Palmas de Gran Canaria, Canary Islands, Spain 2

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To assess the provenance of majolica pottery found in the Canary Islands, a sample of 55 sherds was obtained from two sites on Gran Canaria Island: La Cueva Pintada (Gáldar) and El Antiguo Convento de San Francisco (Las Palmas de Gran Canaria). The pottery was studied by X-ray fluorescence, instrumental neutron activation analysis, and X-ray diffraction. The results show one group that matches a reference group from Seville, an assessment that supports the historical record. However, the data also reveal samples whose provenance corresponds to other production centers on the Iberian Peninsula, such as Manises, Barcelona, and, possibly, an unknown Portuguese center. Moreover, it is possible that Italian and Dutch pottery have been identified thereby providing a complexity factor to the historical accounts.

Introduction The purpose of this paper is to present a preliminary chemical and mineralogical assessment of majolica pottery found on Gran Canaria sites dating from the 15 —16 centuries as evidence of the important trade that occurred th

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© 2007 American Chemical Society

In Archaeological Chemistry; Glascock, M., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2007.


377 between Spain and the newly discovered Americas. This study forms part of an on-going research project focused on the archaeometric characterization of Spain's primary pottery production centers (1-5), and forms part of the Ph.D. research of one of the authors (J. Garcia-Ifiafiez). Majolica is an earthenware pottery characterized by a creamy light-buffcolored paste and an opaque white tin-lead glaze coating the entire outer surface of the vessel. However, the most outstanding feature of the majolica pottery perhaps lies in its decoration, being the subject of numerous studies by art historians. Majolica decorations are produced from metallic oxides that always are applied on top of the tin glaze. Majolica opaque-white glaze is obtained from the addition of opacifying particles of tin oxide (Sn0 ), and from quartz and feldspar inclusions contained within the glazing material. Majolica glaze is essentially sand (Si0 ) and lead. The lead acts as a flux that is necessary to decrease the temperature required for melting S i 0 . The tin-lead glaze and the bubbles produced by the firing process absorb, scatter, and/or reflect incident light, turning what is essentially a transparent glaze into a white one. Due to this opacity, majolica decoration is always applied to the outer surface of the glaze (3, 6, 7). The conquest of the Americas by Spaniards began in 1492. However, this process would not have been possible without conquest of the Canary Islands by Spanish troops just a few years earlier. In that sense, although the Canary conquest started at the end of the 14 century (with the Spanish arrival at Lanzarote), the archipelago was not totally occupied by the Castilian Kingdom until 1494 (with the conquest of Tenerife), two years after the first voyage of Columbus to the Caribbean. The Canary Islands represented the key stopping point for Spanish access to the Americas. Indeed, between the 15 and 18 centuries, the Canary Islands were a required stopover for Spanish trade with the Americas. This was due to the necessity of taking the advantage of the ocean currents and Trade Winds that blow directly to the Caribbean from the eastern Atlantic. Moreover, the Canary Islands signified, for all the Spanish ships, the last geographic region controlled by the Spanish before starting their long opensea voyage. Additionally, the Canary Islands were a forced stop for legal reasons in which the Castilian Kingdom established a rigid control over the trade of items to the New World. In order to supervise the traffic of goods, a bureau of trade was established in 1503, called Casa de Contratacion, only eleven years after discovery of the Americas. The Casa de Contratacion had, for more than 200 years (1503-1717), its primary office in the city of Seville, an inland fluvial port protected from pirate attacks. For that reason, as the commercial trade between the Americas and Europe increased, the port of Seville emerged as Spain's most important trading port because it was the departure point and the final destination for most of the ships that traveled between Spain and the Americas. As a direct result of this organization, Seville became one of the most important production centers for majolica and other types of pottery shipped to the Americas. 2

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Goals and Sampling The main objective of the present work is to study the provenance of majolica pottery found on important Gran Canaria Island archaeological sites that have been subject of archaeological research. Furthermore, by means of archaeometric characterization, the role played by the majolica produced in Seville that was documented historically as an import into the Canary Islands, is also assessed. Majolica from different production centers also is considered, thereby adding a complexity factor to the Canary trade relationships panorama in a historical period when, in theory, a very tight control existed over trade with the Americas.

L a Cueva Pintada La Cueva Pintada is one of the most important Prehispanic settlements on Gran Canaria Island, and is located near the present-day city of Gaidar (Figure 1). The name of this site comes from an exceptional Prehispanic cave, painted with geometrical motifs that were first documented in 1862. The native settlement, of Agaldar, had a continuous occupation from the 6 to the 16 centuries, until it was abandoned after the Spanish conquest. Agaldar was the capital of the main indigenous chiefdom on the island, and after the conquest it was one of the first Spanish settlements. From the 18 century until 1970, the area where the site is located was used for agriculture. Archaeological and conservation work (8, 9) was initiated in 1970. th

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San Francisco Convent The ancient San Francisco convent at Las Palmas de Gran Canaria on Gran Canaria Island was built at the end of the 15 century (Figure 1). It is one of the most important historical sites on the island because it represents the earliest founding of the Franciscan order on the island during the conquest of the Canary Islands. The convent remained active until 1835, when the Franciscans were forced to leave after the lands were confiscated by the Spanish government (i.e., MendizabaPs confiscation). After being used by the Spanish army, the building was abandoned during the mid-20 century. In 1992, the archaeological section of the Museo Canario de Las Palmas de Gran Canaria initiated an archaeological excavation of the San Francisco convent remains. A large quantity of majolica pottery, not only Spanish, but also of Italian and Portuguese origin was recovered. Pottery recovered from the archaeological site of the San Francisco convent was classified, on the basis of stylistic attributes, into three main categories: (1) cuerda seca, a hispano-mudejar unglazed pottery, probably produced in Southern th

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Figure 1. Map of the main sites cited in the text. 1: Delft; 2: Liguria; 3: Barcelona; 4: Vilafranca del Penedès; 5: Lleida; 6: Muel; 7: Villafeliche; 8: Reus; 9: Teruel; 10: Patenta; 11: Mortises; 12: Talavera de la Reina; 13: Puente del Arzobispo; 14: Seville; 15: Cueva Pintada; 16: San Francisco's convent.

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Spain during 15 and first half of the 16 centuries; (2) Spanish and Italian 16 century majolica—primarily white and blue-on-white, and (3) Portuguese faience dating to the 17 century (10). th

Sampling and Methods A l l samples analyzed from L a Cueva Pintada and the San Francisco convent were selected based their chronology and typology. From the site of L a Cueva Pintada, 18 majolica and glazed pottery sherds, dating from the late 15 and 16 centuries were selected (Table I); 37 sherds from the San Francisco convent, mostly majolica, dating from the late 15 to 17 centuries also were obtained (Table II). Most of the analyzed majolica are plain white or exhibit blue patterns over an opaque white background. Nevertheless, a few of the specimens show different decorations, such as polychrome or green-on-white motifs. A few of the sherds from L a Cueva Pintada exhibit a transparent lead glaze coating which is green or honey colored. th

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Forty-four of the 55 samples were chemically characterized by X-ray fluorescence (XRF). Thirty-seven of these samples were also characterized mineralogically by X-ray diffraction (XRD). Finally, 11 out of the 44 samples analyzed by X R D (4 specimens from L a Cueva Pintada site and 7 from the San Francisco's convent) were analyzed by instrumental neutron activation analysis (INAA). Additionally, 11 samples from San Francisco convent, which had an insufficient weight to be characterized by X R F , were analyzed by I N A A as well. X R D analyses are now being conducted for the 18 samples not yet characterized.

Analytical Procedure and Data Analysis In the present study, 12 g from each sherd was collected. Glazes and other surfaces were mechanically removed to minimize contamination from glaze and other external compounds. Following this process, specimens were powdered and homogenized in a Spex Mixer (Mod. 8000) tungsten carbide cell mill for 12 minutes. Powdered specimens were transferred to clean polyethylene vials for transportation to the laboratory. The chemical compositions of the samples analyzed by X R F were determined using a Phillips P W 2400 spectrometer with a Rh excitation source. Samples were prepared for analysis using two different methods. Duplicates of glassy pills made by fusing 0.3 g of dry powder with 5.7 g of L i B 0 to determine the major and minor elements with the exception of N a 0 . Trace elements and N a 0 were determined from 5 g pills of powdered dry sample. The quantification of the concentrations was obtained using a calibration line based on 60 international geological standards. The elements determined were F e 0 (as total Fe), A 1 0 , M n O , P 0 , T i 0 , MgO, CaO, N a 0 , K 0 , S i 0 , Ba, Rb, Mo, Th, Nb, Pb, Zr, Y , Sr, Sn, Ce, Co, Ga, V , Zn, W, Cu and N i . The loss on ignition (LOI) was determined by firing 0.3 g of dried powder at 950°C for three hours. A n extended description of the X R F analytical procedures, including the details of accuracy and precision, has been published elsewhere (11). Chemical analyses by I N A A were conducted at the Archaeometry Laboratory at the Missouri University Research Reactor Center ( M U R R ) . Aliquots of sample were oven-dried at 100 °C for 24 h. Amounts of approximately 150 mg were weighed into small polyvials used for short irradiations. At the same time, 200 mg of each sample was weighed into highpurity quartz vials used for long irradiations. Along with the majolica samples, reference standards of SRM-1633a (coal fly ash) and SRM-688 (basalt rock) were similarly prepared, as well as quality control samples of SRM-278 (obsidian rock) and Ohio Red Clay (standards treated as unknowns). 1

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The X R F and X R D analyses were conducted by the Scientific-Technical Services laboratory at the University of Barcelona.


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Table I. Summary of Samples from L a Cueva Pintada Site Sample ID MJ0236 MJ0237 MJ0238 MJ0239 MJ0240 MJ0241 MJ0242 MJ0243 MJ0244 MJ0245 MJ0246 MJ0247 MJ0248 MJ0249 MJ0250 MJ0251 MJ0252 MJ0253

XRF

Description Lusterware Sevillan White Blue-on-white Green Blue tile Sevillan White Blue-on-white Blue-on-white Honey Honey Blue-on-white Blue Honey Green Green Honey Honey Green

XRD

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

INAA χ χ

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Classification Manises Seville Seville Ungrouped Seville Seville Seville Seville Ungrouped Seville Seville Seville Seville Ungrouped Seville Ungrouped Ungrouped Seville

At M U R R , I N A A of pottery consists of two irradiations and three gamma counts. Short irradiations involve a pair of samples being transported through a pneumatic tube system into the reactor core for a 5 s neutron irradiation at a flux of 8 X 10 η cm" -s" . Following a 25-min decay, the samples are counted for 720 s using a high-resolution germanium detector. This count yields data for nine short-life elements: A l , Ba, Ca, Dy, Κ, M n , Na, T i and V . For the long irradiation, bundles of 50 or 100 of the encapsulated quartz vials are irradiated for 24 h at a flux of 5 Χ ΙΟ η cm'V . After the long irradiation, samples are permitted to decay for seven days, and then are counted for 2000 s (known as "mid count") on a high-resolution germanium detector coupled to an automatic sample changer. This mid count yields data for seven medium half-life elements: As, La, L u , N d , Sm, U , and Y b . After an additional two-week decay, a second count of 10,000 s is carried out on each sample. This measurement allows quantification of 17 long-life elements: Ce, Co, Cr, Cs, Eu, Fe, Hf, N i , Rb, Sb, Se, Sr, Ta, Tb, Th, Zn, and Zr (12). The mineralogical composition of all the samples included in the study was determined by X R D , using the same powdered sample prepared for X R F analysis. Measurements were performed using a PANalytical X'Pert PRO alphal powder diffractometer (radius = 240 mm) using the Cu Κα radiation (λ = 1.5418 Â), with a working power of 45 k V - 40 mA. The incident beam was passed through a 0.04 radians Soller slit, and the diffracted beam passed through a second slit. Moreover, the diffracted beam was N i filtered. A n X'Celerator 13

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Table II. Summary of Samples from San Francisco Convent Site Simple ID MJ0254 MJ0255 MJ0257 MJ0258 MJ0259 MJ0260 MJ0261 MJ0262 MJ0263 MJ0264 MJ0265 MJ0266 MJ0268 MJ0269 MJ0270 MJ0271 MJ0272 MJ0273 MJ0274 MJ0275 MJ0276 MJ0277 MJ0278 MJ0280 MJ0281 MJ0282 MJ0284 MJ0285 MJ0286 MJ0287 MJ0288 MJ0289 MJ0290 MJ0291 MJ0292 MJ0293 MJ0294

Description Lusterware Lusterware Columbia Simple Columbia Simple Columbia Simple Columbia Simple Sevillan White Sevillan White Sevillan White Sevillan White Sevillan White Sevillan White Isabela Polychrome Delft series Ligurian blue-on-white Ligurian blue-on-white Ligurian blue-on-white Ligurian blue-on-white Ligurian blue-on-white Portuguese blue-on-white Portuguese blue-on-white Portuguese blue-on-white Italian Polychrome Ichtuknee blue-on-blue Ichtuknee blue-on-blue Ichtuknee blue-on-blue Sgraffito Lusterware Lusterware Columbia Simple Sevillan White Delft series Ligurian blue-on-white Ligurian blue-on-white Portuguese blue-on-white Catalan blue-on-white Green and Manganese

XRF

XRD

X

X

INAA

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X X X X X X X

X X X X X X X X X X X

Classification Manises Seville Seville Seville Seville Ungrouped Seville Seville Seville Seville Seville Seville Seville Ungrouped Ligurian Ligurian Ligurian Ligurian Ligurian Portuguese Portuguese Portuguese Ligurian Seville Seville Seville Ungrouped BCN-SC Seville Seville Seville Seville Ligurian Ligurian Portuguese BCN-SC Ungrouped


383 Detector, with active length = 2.122 °, was used. Θ/2Θ scans were reorded from 4 to 70 2Θ (step size=0.017°; time=50 s per step). The evaluation of crystalline phases was carried out using the D I F F R A C T / A T program by Siemens, which includes the Joint Committee of Powder Diffraction Standards (JCPDS) data bank. 0


Data Treatment Although sample preparation was conducted under great care to minimize the analytical error, the potential for contamination does exist. As a precaution, tungsten and cobalt were removed from consideration during the statistical analysis of data because samples were powdered using a tungsten carbide cell grinder in which W is a major component and Co is a minor component. Additionally, the technology of majolica pottery production is characterized by Sn and high Pb in their glazes, causing analytical problems because of their diffusion into the clay matrix body. Therefore, Sn and Pb concentrations have not been considered because of the possibility of contamination from the glaze. Moreover, chemical results have shown that Pb content largely exceeds the upper X R F regression limit (928 ppm) (Figure 2). In X R F , unusually high Pb results in interferences with nearby peaks. Thus, trace elements such as Ga and Y , and Th and Rb, might have high error. Consequently, these elements were not considered in the analysis of the X R F data. Moreover, M o , as determined by X R F , is always below the lower detection limit and cannot accurately be determined. Finally, the element N i was below the detection limits in most samples analyzed by I N A A and was subsequently removed from consideration. For statistical analysis, the D-compositional chemical data were transformed into log-ratios following Aitchison's and Buxeda's recommendations, by taking the natural logarithm of the ratio of all determined components to one component selected as the divisor according to the equation

i /

xGS ->y = l n ( ^ ) € R

i /

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where x_ =(xi,...,x ) (13, 14). The variation matrix was used as an exploratory tool to identify sources of compositional variability, to quantify this variability, and to identify the appropriate element to be used as a divisor in the log-ratio transformation (75). Canary Island specimens were compared against several reference groups already established for the primary productions centers on the Iberian Peninsula. To date, 425 samples (Table III) have been chemically analyzed and reference groups have been defined for Barcelona, Reus, Vilafranca del Penedès, Lleida, Paterna, Manises, Muel, Teruel, Villafeliche, Talavera de la Reina, Puente del Arzobispo and Seville (Figure 1). A l l 425 D

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384 samples have been also mineralogically characterized by X R D . However, the analyses for 15 samples from Lleida, and 57 samples from Seville, corresponding to the kiln sites of Pureza (attributed to Niculoso Pisano), Valladares, and Plaza de Armas, are still in process.

Results and Discussion


X R F Data The variation matrix generated for the X R F data exhibits a total variation (vt) of 2.034 which can be considered high (15). The components responsible for most of this variability are P 0 , Cu, N a 0 , Sr, K 0 , CaO, M g O , N i and B a (vt/τ j

Century Majolica Pottery Found on the Canary Islands - American

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