Study of forge slags from the Roman site of Forua (Bizkaia)

The archaeological site of Forua (Bizkaia) corresponds to an iron production centre of the Roman period (1st–3rd centuries AD). The distribution of the workshops joint to the type of slags indicates that correspond to a set of forging furnaces. The micro-textural and mineralogical features of the studied materials allow us to differentiate three groups, two of them correspond to forge slags, while the other group represents the ore mineral. These two types of slag indicate different stages in the production of iron from ferriferous spongeEl yacimiento arqueológico de Forua (Bizkaia) corresponde a un centro de producción de hierro en época romana (s. I–III). La distribución de los talleres junto con el tipo de restos encontrados indican que se trata de un conjunto de hornos de forja. Las características mineralógicas y microtexturales de los materiales ferruginosos estudiados permiten diferenciar tres grupos, dos de ellos corresponden a escorias de forja, mientras que el otro representa la mena de hierro. Los dos tipos de escorias indican estadios diferentes en la obtención del hierro a partir de la esponja ferrífer

Compositional Characterization and Chronology of Roman Mortars from the Archaeological Site of Arroyo De La Dehesa De Velasco (Burgo De Osma- Ciudad De Osma, Soria, Spain)

This study characterises the mortar materials used in the construction of walls and floors at the Arroyo de la Dehesa de Velasco site, located near the Roman city of Uxama Argaela (the modern Burgo de Osma—Ciudad de Osma, Soria, Spain). Multilayer mortars have been characterised by petrographic, mineralogical (X-ray diffraction and scanning electron microscopy with energy dispersive analyses and geochemical analysis (X-ray fluorescence). Additionally, radiocarbon dating of the mortar binder fraction was performed in order to establish the chronology of the building in the absence of other archaeological chronological records. The results showed that similar siliceous aggregates and lime binders were used in the fabrication of multilayer system mortars. Some multilayer wall mortars show ceramic fragments or brick powder to produce hydraulic mortars and improve the resistance to moisture. The raw materials used for the construction of the site were of local origin and the construction was built during the first century BC, according to radiocarbon dating.This study was partially supported by the T1193-13 project of the Basque Country Government

Strontium and oxygen isotopes to trace mobility routes during the Bell Beaker period in the north of Spain

[EN]Strontium and oxygen isotopes of individuals from El Hundido and Valdescusa (north of Spain) sites, corresponding to the Bell Beaker culture, were analysed in order to determine mobility patterns and provenance areas. Strontium and oxygen isotope ratios in three teeth from two individuals at El Hundido and two teeth from the five individuals at Valdescusa were studied. The analyses were performed in both dentine and enamel fractions. Sr-87/Sr-86 ratios of El Hundido individuals indicate one was of foreign origin and the other was local whereas at Valdescusa were all of foreign provenance. Calculated delta O-18(w) values of El Hundido suggest a provenance from the geographical area close to the site while the Valdescusa would come from a warmer region. The comparison of oxygen and strontium isotope signatures indicate the west of the Iberian Peninsula (Zamora or the east of Leon regions) as the provenance area for the foreign individual at El Hundido and southwest France (Garonne basin) as the region of provenance for the Valdescusa.This work has been supported financially by Research Group IT1193-19 and PIBA 2018_1_0053 research projects of the Government of the Basque Country

Hydrotalcite and Hydrocalumite in Mortar Binders from the Medieval Castle of Portilla (Álava, North Spain): Accurate Mineralogical Control to Achieve More Reliable Chronological Ages

Mortars from different stratigraphic units at Portilla Castle (Alava, North Spain) have been analyzed for mineralogical characterization before radiocarbon dating. The mortar binder at Portilla Castle is composed not only of neoformation calcite but also of double-layered hydroxide (LDH) minerals such as hydrotalcite and hydrocalumite. The mineralogy of several fractions of the binder has been analyzed to determine the granulometric distribution of minerals in the binder. The continuous monitoring of mineralogy during the extraction of different grain size fractions has been performed by using a scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analyses (TGA). Hydrotalcite and hydrocalumite-bearing mortar binders give older ages than expected since they introduce dead carbon into the system.This research was possible thanks to the financial support of SAI13/106 research project of Basque Country Government

Mineralogical Characterization of Slags from the Oiola Site (Biscay, Spain) to Assess the Development in Bloomery Iron Smelting Technology from the Roman Period to the Middle Ages

The Oiola archeological site, located in the mining complex of La Arboleda (Biscay, North Spain)was an important iron smelting center from the Roman Period to the Middle Ages and even in more current times (19th–20th centuries). Tap-slags and some plano-convex slags were identified as smelting slags. Samples were analyzed by optical microscopy, X-ray powder diffraction, scanning electron microscopy coupled with electron-dispersive spectroscopy and Raman microspectroscopy to perform a mineralogical and textural characterization. Additionally, thermogravimetric and thermodiffraction analyses were carried out to determine furnace operating temperatures. The mineral assemblage reflects furnace temperatures and cooling rates and the addition of quartz as the main flux to decrease the melting temperature of the iron ore. The comparison of slags from the Roman Period and the Middle Age reveals changes in the pyrometallurgical process through time.H.P.-B. would like to thank the PRE-2019-2-0138 PhD research grant of the Basque Country Government and the SGIker service at the University of the Basque Countr

Trade Networks in the Neighbouring Roman Provinces of Aquitania-Tarraconensis on the Bay of Biscay: Evidence from Petrographic and Chemical Analyses of Common Coarse Ware Pottery

Common non-wheel-thrown Roman pottery from the southern Aquitania and north-eastern of Tarraconensis provinces (CNT-AQTA) of the Early and Later Roman Empire (1st to 5th centuries AD) has been studied. Petrological, mineralogical, and chemical analyses were conducted to contrast with the archaeological study of the pottery. The chemical composition of many pottery samples displays different patterns of burial chemical modification, limiting their use for provenance and diffusion studies. Particular emphasis has been paid to the petrographic features of the fabrics, as they do not change during burial, reflecting the nature of the raw material and making it possible to identify the provenance areas of the raw materials. Around the Bay of Biscay, the same pottery tradition continued in the neighbouring provinces during Roman times. Petrographic studies make it possible to determine the distribution of pottery and the changes in trade networks during the Roman period across the area of the Bay of Biscay being studied.This research was funded by Fundación José Miguel de Barandiaran Fundazioa, grant number 2004, and the Basque Country government, grant number IT1442-22. The APC was funded by the Basque Country government, grant number IT1442-22

Multispectroscopic methodology to study Libyan desert glass and its formation conditions

Libyan desert glass (LDG) is a melt product whose origin is still a matter of controversy. With the purpose of adding new information about this enigma, the present paper analyzes the inner part of LDG specimens and compares them with the results of LDG surfaces. An integrated analytical methodology was used combining different techniques such as Raman spectroscopy, in point-by-point and imaging modes, scanning electron microscopy with X-ray microanalysis (SEM-EDS), energy-dispersive micro X-ray fluorescence spectrometry (μ-EDXRF), electron probe micro analyzer (EPMA), and optical cathodoluminescence (Optical-CL). According to our results, flow structures of the melt and the amorphous nature of the matrix could be discerned. Moreover, the observed displacement of Raman bands, such as in the cases of quartz and zircon, and the identification of certain compounds such as coesite (the most clarifying phase of high pressures), α-cristobalite, gypsum, anhydrite, corundum, rutile, amorphous calcite, aragonite, and calcite allowed us to know that LDGs could be subjected to shock pressures between 6 and more than 30 GPa, and temperatures between 300 and 1470 °C. The differences of temperature and pressure would be provoked by different cooling processes during the impact. Besides, in most cases the minerals corresponding to high pressure and temperatures were located in the inner part of the LDGs, with some exceptions that could be explained because they were trapped subsequently to the impact; there was more than one impact or heterogeneous cooling. Furthermore, nitrogen and oxygen gases were identified inside bubbles, which could have been introduced from the terrestrial atmosphere during the meteorite impact. These data helped us to clarify some clues about the origin of these enigmatic samples.Proyecto MINECO Retos de la Sociedad. Ref. ESP2014-56138-C3-2-

Isotope analyses to explore diet and mobility in a medieval Muslim population at Tauste (NE Spain)

The Islamic necropolis discovered in Tauste (Zaragoza, Spain) is the only evidence that a large Muslim community lived in the area between the 8th and 10th centuries. A multi-isotope approach has been used to investigate the mobility and diet of this medieval Muslim population living in a shifting frontier region. Thirty-one individuals were analyzed to determine delta N-15, delta C-13, delta O-18 and Sr-87/Sr-86 composition. A combination of strontium and oxygen isotope analysis indicated that most individuals were of local origin although three females and two males were non-local. The non-local males would be from a warmer zone whereas two of the females would be from a more mountainous geographical region and the third from a geologically-different area. The extremely high delta(15) N baseline at Tauste was due to bedrock composition (gypsum and salt). High individual delta(15) N values were related to the manuring effect and consumption of fish. Adult males were the most privileged members of society in the medieval Muslim world and, as isotope data reflected, consumed more animal proteins than females and young males.Research Group GIU15/34 of the University of the Basque provided support to MO, XM, Country-UPV/EHU, http://www.ehu.eus/es/web/ikerkuntza. IT315-10 Research Group of the Basque Country Government provided support to IG LO MCZ, http://www.hezkuntza.ejgv.euskadi.eus/r43-5553/es/