Northern exposure: Baltic amber and silver beads from the Iron Age reuse of the Bela Vista tholos (Sintra, Portugal)

Vientos del norte: el ámbar báltico y las cuentas de plata de la reutilización en la Edad del Hierro del tholos de Bela Vista (Sintra, Portugal)

José Ángel Garrido-Cordero Departamento de Prehistoria y Arqueología, Universidad de Sevilla / UNIARQ - Centro de Arqueologia da Universidade de Lisboa, Universidade de Lisboa, jgarrido8@us.es
Rita Loureiro UNIARQ - Centro de Arqueologia da Universidade de Lisboa, Universidade de Lisboa, ritasloureiro@edu.ulisboa.pt
José María Martínez-Blanes Departamento de Química Inorgánica, Universidad de Sevilla, blanes@us.es
Ana C. Sousa UNIARQ - Centro de Arqueologia da Universidade de Lisboa, Universidade de Lisboa, sousa@edu.ulisboa.pt
María Dolores Zambrana-Vega Departamento de Pintura, Universidad de Sevilla, mzambrana@us.es
Luz Marina Salas Acosta Departamento de Dibujo, Universidad de Sevilla, luzmar@us.es
Daniel Sánchez-Gómez UNIARQ - Centro de Arqueologia da Universidade de Lisboa, Universidade de Lisboa, dasa39@gmail.com
Carlos P. Odriozola Departamento de Prehistoria y Arqueología, Universidad de Sevilla / UNIARQ - Centro de Arqueologia da Universidade de Lisboa, Universidade de Lisboa, codriozola@us.es (corresponding author)

ABSTRACT

RESUMEN

CONTENIDO

1. INTRODUCTION  ⌅

Amber has long captivated researchers due to its distinctive physical properties—its vibrant color, transparency, lightness, and aromatic qualities—as well as its rarity and origins in distant geological sources. Beyond its aesthetic appeal, amber plays a crucial role in archaeological research as a key material for reconstructing prehistoric exchange networks. Its geochemical composition allows for the identification of its geographical provenance through scientific analysis, offering valuable insights into long-distance interactions and mobility in the past.

Despite amber’s archaeological significance, systematic studies in the Iberian Peninsula only became possible in the mid-20^th century. A major breakthrough came with Beck’s pioneering application of Fourier-Transform Infrared Spectroscopy (FTIR) (Beck et al., 1964Beck, C. W., Wilbur, E. and Meret, S. (1964). “Infra-Red Spectra and the Origin of Amber”. Nature, 201 (4916), pp. 256-257. DOI: https://doi.org/10.1038/201256a0.), which enabled researchers to determine the origin of amber samples. This advancement spurred dedicated research into Iberian amber trade, beginning with Ferreira’s (1966)Ferreira, O. da V. (1966). “Os artefactos préhistóricos de ámbar e sua distribuição em Portugal”. Revista de Guimarães, 76 (1-2), pp. 61-66. inventory of prehistoric amber in Portugal and later expanded by Vilaça’s comprehensive review of Portuguese amber artifacts (Vilaça et al., 2002Vilaça, R., Beck, C. W. and Stout, E. C. (2002). “Provenience analysis of prehistoric amber artifacts in Portugal”. Madrider Mittelungen, (43), pp. 61-78.). However, it was not until the synthesis by Murillo-Barroso and Martinón-Torres (2012)Murillo-Barroso, M. and Martinón-Torres, M. (2012). “Amber Sources and Trade in the Prehistory of the Iberian Peninsula”. European Journal of Archaeology, 15 (2), pp. 187-216. DOI: https://doi.org/10.1179/1461957112y.0000000009. that a truly systematic overview of Iberian amber based on FTIR analysis emerged. This laid the foundation for subsequent provenance studies across the peninsula (Peñalver and Delclòs, 2010Peñalver, E. and Delclòs, X. (2010). “Spanish amber”. In: Penney, D. (Ed.). Biodiversity of fossils in amber from the major world deposits. Manchester: Siri Scientific Press, pp. 236-270.; Murillo-Barroso et al., 2018Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.; Odriozola et al., 2019Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7.; Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.; Romero-García et al., 2024Romero-García, G., Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., Sousa, A. C. and Odriozola, C. P. (2024). “Unlocking archaeological data online via the PEPAdb (Prehistoric Europe’s Personal Adornment Database) initiative for Open Science”. Antiquity, 98 (398), pp. 1-6. DOI: https://doi.org/10.15184/aqy.2024.2.) and enabled the construction of a chronological model of amber consumption in Iberia from Late Paleolithic to the Iron Age. This model reveals a major shift in supply patterns: whereas Sicilian amber dominated between the 5^th and 2^nd millennia BCE, Baltic amber became increasingly prevalent from the 2^nd millennium BCE onward (Odriozola et al., 2019Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7.; Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.). Notably, FTIR-based provenance has recently been proposed as a chronological proxy for undated amber artifacts, offering a powerful tool for contextualizing ambiguous finds (Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.).

Nonetheless, important challenges remain. The degradation of amber through oxidation and polymerization has rendered many artifacts unrecognizable or entirely destroyed. In addition, inconsistencies in early excavation records, misclassification in museum collections, and the loss of materials during analytical procedures have introduced significant gaps in the archaeological record. The most recent inventory of Iberian amber (Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.) documents 781 objects from 85 sites. However, five beads from five different sites remain unaccounted for—among them, the amber bead from Bela Vista, which has long been presumed lost.

Recently rediscovered in a fragmented and deteriorated condition at the Museu dos Serviços Geológicos de Portugal (Fig. 1), the Bela Vista bead offers a rare opportunity to reassess its provenance, chronology, and significance within prehistoric exchange systems. This study combines FTIR analysis of the amber bead with mineralogical characterization (MACLAS¹1 Mineral archaeological classification System (Sánchez-Gómez et al., 2024).) and provenance tracing (VORTEX²2 Variscite origin recognition technology X-ray based (Sánchez-Gómez et al., 2025, 2026).) of associated greenstone beads to clarify their origins and cultural meaning. Through the integration of these analytical approaches, we aim to:

1. Determine the amber’s provenance and assess its implications for Iberian exchange networks.
2. Reconstruct the bead’s chronological context, evaluating whether it corresponds to the Copper Age or the Iron Age.

The Bela Vista tholos, a megalithic tomb located in the Sintra necropolis, exhibits a complex stratigraphy with materials spanning from the Copper Age to the Iron Age. By comparing the remaining assemblage with parallels from other archaeological contexts, we argue that the amber bead most likely dates to the Iron Age (7^th-5^th centuries BCE), a period marked by the expansion of Baltic amber trade into the Iberian Peninsula.

2. THE BELA VISTA THOLOS  ⌅

The tholos of Bela Vista (CNS [Código Nacional de Sítio] 19452, 38.791550 N, -9.424610 [WGS84, EPGS:4326]) is a distinctive megalithic monument located within the Sintra megalithic necropolis (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.; Leisner, 1965Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter.; Boaventura, 2009Boaventura, R. (2009). As antas e o Megalitismo da região de Lisboa. Ph.D. Thesis, Universidade de Lisboa. Facultade de Letras, Departamento de História. Available at: http://repositorio.ul.pt/handle/10451/587 (accessed September 9, 2014)., pp. 216-217) (Fig. 2). Discovered in 1957 and excavated between 1957 and 1959, the monument is classified either as a pseudo-tholos (Boaventura, 2009Boaventura, R. (2009). As antas e o Megalitismo da região de Lisboa. Ph.D. Thesis, Universidade de Lisboa. Facultade de Letras, Departamento de História. Available at: http://repositorio.ul.pt/handle/10451/587 (accessed September 9, 2014)., p. 217) or an hybrid monument (Sousa, 2016Sousa, A. C. (2016). “Megalitismo e Metalurgia. Os Tholoi do Centro e Sul de Portugal”. In: Sousa, A. C., Carvalho, C. and Viegas, C. (Eds.). Terra e Água. Escolher sementes, invocar a Deusa. Estudos em Homenagem a Victor S. Gonçalves. Estudos e Memórias 9. Lisboa, UNIARQ-FLUL, pp. 209-241., p. 223). The tomb is constructed among large granite outcrops and features a mixed stone masonry structure. While no vaulted dome has been identified, there is evidence of a substantial earthen mound (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.; Pina, 2019Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555.).

Excavations revealed three stratigraphic layers (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.):

– C3: The uppermost layer, consisting of humus, black topsoil, and modern-era debris.

– C2: Located between C3 and C1, this intermediate layer contained a mixed assemblage of ceramics ranging from the Iron Age to the medieval period. Due to extensive post-depositional disturbance, no discrete stratification could be distinguished.

– C1: The lowest layer, directly beneath C2, was interpreted by the excavators as a predominantly prehistoric burial layer. Although partially disturbed, it was considered to represent a relatively intact Eneolithic (Iberian Copper Age, 3^rd millennium BCE) context, with a minimum number of individuals (MNI) estimated at three (Pina, 2019Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555.).

Level C1 at Bela Vista yielded a diverse assemblage of artifacts spanning multiple periods. Notably, several Iron Age elements were recovered from this level, including wheel-thrown pottery fragments, a ceramic loom weight, and a silver arc fibula of Hallstatt type³3 Também nos níveis superiores à camada eneolítica [refers to C1] foram encontrados muitos restos de cerâmicas de várias épocas assim como um peso de tear de idade do ferro e uma mola de prata de una fíbula de arco de tipo Hallstat (Mello et al., 1961, p. 246). Translation to English: Also, in the levels above the Eneolithic layer [refers to C1] many remains of ceramics from various periods were found, as well as an Iron-Age loom weight and a silver spring from a Hallstat-type bow fibula. (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.). These materials are clearly intrusive, contrasting with the core funerary assemblage, which includes handmade pottery, flint blades and flakes, an amphibolite axe head, a bone awl, two gold coils (now lost), an ivory V-perforated button, Palmela points, and eleven Bell Beaker vessels—objects that can be confidently attributed to the 3^rd millennium BCE (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.; Leisner, 1965Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter.; Pina, 2019Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555.).

A particularly intriguing subset of this assemblage is a group of six beads—four made of greenstone, one of amber, and one of ceramic (Tab. 1; Fig. 3). Unfortunately, the original excavation records lack precise information regarding their findspot within Level C1 or their association with human remains or specific grave goods. This absence of detailed contextual data hampers interpretations of their chronological placement and ritual significance. Further complicating matters, museum catalogues group all artifacts under a general ‘Bela Vista’ label, without any stratigraphic distinctions or provenience metadata, obscuring the relationship between objects from different periods.

Although beads are typically produced for use as personal adornments—such as necklaces, bracelets, anklets, pendants, or buttons—they are rarely found in direct association with specific individuals in megalithic burial contexts (Odriozola et al., 2020Odriozola, C. P., Garrido-Cordero, J. Á., Santos, C., Barradas, E. and Sousa, A. C. (2020). “The stone beads from Barrada’s hypogeum 1 (Aljezur, Algarve, Portugal). Greenstone distribution patterns in the Iberian Southwest late Neolithic”. Journal of Archaeological Science: Reports, 34, 102667. DOI: https://doi.org/10.1016/j.jasrep.2020.102667.). At Bela Vista, as in many other sites, beads were recovered from the basal levels of the burial layer, often scattered and not clearly linked to skeletal remains. In this case, only three teeth, several phalanges, and a skull cap fragment were found, making it impossible to determine whether the bead assemblage belonged to a specific individual or burial episode (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.).

3. THE AMBER BEAD OF BELA VISTA: A REDISCOVERY  ⌅

The amber bead from Bela Vista was first documented by Otávio da Veiga Ferreira in his catalogue of prehistoric Portuguese amber artifacts, where he described it as a small, brown, slightly translucent bead, fragile and poorly preserved (Ferreira, 1966Ferreira, O. da V. (1966). “Os artefactos préhistóricos de ámbar e sua distribuição em Portugal”. Revista de Guimarães, 76 (1-2), pp. 61-66., p. 63). Despite this early reference, the bead subsequently vanished from scholarly view. During the first archaeometric study of Portuguese amber artifacts, Vilaça and colleagues were unable to locate it in the collections of the Museu dos Serviços Geológicos de Portugal (Vilaça et al., 2002Vilaça, R., Beck, C. W. and Stout, E. C. (2002). “Provenience analysis of prehistoric amber artifacts in Portugal”. Madrider Mittelungen, (43), pp. 61-78., p. 74), leading to the widespread assumption that the object had been lost (Odriozola et al., 2019Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7., p. 572).

Aside from the original excavators (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.) and the last researchers known to have seen the bead (Leisner, 1965Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter., p. 85; Ferreira, 1966Ferreira, O. da V. (1966). “Os artefactos préhistóricos de ámbar e sua distribuição em Portugal”. Revista de Guimarães, 76 (1-2), pp. 61-66.), no subsequent documentation of its whereabouts has existed. This lacuna persisted even during Pina’s (2019)Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555. comprehensive review of the Bela Vista assemblage, which failed to relocate the artifact. The rediscovery of the amber bead by our team has resolved this decades-long uncertainty. Its identification corrects the archaeological record and enables new investigations into its composition, provenance, and cultural significance—issues that could not previously be addressed due to its presumed loss.

4. DISCREPANCIES IN DESCRIPTIONS OF THE BEAD ASSEMBLAGE  ⌅

The bead assemblage from Bela Vista has been described inconsistently over time, with notable discrepancies among key publications by Mello et al. (1961)Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249., Leisner (1965)Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter., and Pina (2019)Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555.. These inconsistencies have led to confusion regarding the composition and classification of the materials. A summary of the divergent accounts is presented in Tab. 2.

5. METHODOLOGY  ⌅

5.1. Amber provenance and chronological analysis

Amber provenance was determined using Fourier-Transform Infrared Spectroscopy (FTIR), a well-established technique for distinguishing between amber types based on their diagnostic spectral characteristics. For example, Baltic amber is identified by its characteristic ‘Baltic shoulder’, consisting of prominent absorption peaks between 1160 and 1150 cm⁻¹, preceded by a broad horizontal band spanning 1250-1180 cm⁻¹ (Beck et al., 1964Beck, C. W., Wilbur, E. and Meret, S. (1964). “Infra-Red Spectra and the Origin of Amber”. Nature, 201 (4916), pp. 256-257. DOI: https://doi.org/10.1038/201256a0., 1965Beck, C. W., Wilbur, E., Meret, S., Kossove, D. and Kermani, K. (1965). “The Infrared Spectra of Amber and the Identification of Baltic Amber”. Archaeometry, 8 (1), pp. 96-109.; Beck, 1982Beck, C. W. (1982). “Authentication and conservation of amber: conflict of interests”. Studies in Conservation, 27 (sup1), pp. 104-107. DOI: https://doi.org/10.1179/sic.1982.27.Supplement-1.104., 1986Beck, C. W. (1986). “Spectroscopic Investigations of Amber”. Applied Spectroscopy Reviews, 22 (1), pp. 57-110. DOI: https://doi.org/10.1080/05704928608060438.). In contrast, Sicilian amber exhibits a principal band at 1245 cm⁻¹, accompanied by secondary bands around 1182 cm⁻¹ (Beck and Hartnett, 1993Beck, C. W. and Hartnett, H. E. (1993). “Sicilian amber”. In: Beck, C. W. and Bouzek, J. (Eds.). Proc. 2nd Int. Conf. Amber in Archaeology. Liblice. 1990. Prague: Czech Academy of Sciences, pp. 36-47.; Angelini and Bellintani, 2005Angelini, I. and Bellintani, P. (2005). “Archaeological ambers from northern Italy: an FTIR–drift study of provenance by comparison with the geological amber database”. Archaeometry, 47 (2), pp. 441-454. DOI: https://doi.org/10.1111/j.1475-4754.2005.00212.x.). Iberian Cretaceous ambers are characterized by peaks at 1456, 1376, 1155, and 1030 cm⁻¹, along with a secondary feature at 1226 cm⁻¹ (Peñalver et al., 2007Peñalver, E., Álvarez-Fernández, E., Arias, P., Delclòs, X. and Ontañón, R. (2007). “Local amber in a Palaeolithic context in Cantabrian Spain: the case of La Garma A”. Journal of Archaeological Science, 34 (6), pp. 843-849. DOI: https://doi.org/10.1016/j.jas.2006.03.006.; Murillo-Barroso et al., 2018Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.).

The provenance of the amber bead from Bela Vista was determined by comparing its FTIR spectrum to these reference profiles. Spectral data were collected using a Nicolet iS5 FTIR spectrometer with an iD7 ATR module. Each sample was scanned 64 times across the 4000-525 cm⁻¹ range, at a resolution of 4 cm⁻¹. This procedure ensures high accuracy and reproducibility, facilitating a reliable provenance determination.

In order to contextualize the bead chronologically, the FTIR results were integrated with stratigraphic and typological data (Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.). This included evaluating the bead’s stratigraphic position, associations with other artifacts, and typological traits. These data were cross-referenced with established chronological frameworks for amber consumption on the Iberian Peninsula, enabling assessment of whether the bead corresponds to the Bronze Age, Iron Age, or an earlier period.

5.2. Elemental composition and provenance analysis of greenstone beads (‘callaite’)

The greenstone beads—historically labeled as ‘callaite’—were analyzed using the MACLAS framework, a supervised machine learning (ML) approach for mineral identification based on elemental composition. MACLAS employs a gradient boosting classifier trained on geochemical data to distinguish both major mineral classes (e. g., phosphates, silicates) and specific mineral species (e. g., variscite, muscovite), with confidence scores indicating the reliability of each classification. This non-destructive method enables fast and accurate mineral identification.

For beads identified as phosphate minerals, their provenance was further assessed using the VORTEX (Variscite Origin Recognition Technology X-ray based) framework. VORTEX applies a Random Forest classifier trained on a comprehensive dataset of Iberian variscite sources, enabling probabilistic assignment of beads to specific geological deposits. The model provides accurate provenance predictions with a confidence threshold of >0.7, and has been externally validated, achieving 95 % accuracy in source classification.

Elemental composition data were obtained using an Oxford Instruments XMET-7500 handheld X-ray fluorescence (XRF) spectrometer, equipped with a rhodium X-ray tube, silicon drift detector (SDD), and an automated 5-position filter changer. Quantification was conducted using the SOILS-LE calibration program, which applies the fundamental parameters (FP)⁴4 Each sample was analyzed for approximately 60 seconds, with all chemical elements from magnesium (Mg) to uranium (U) measured and quantified. To ensure accuracy, 32-mm pellets of certified reference materials (BCR-032 #919 and GMB306-12) were analyzed at the beginning and end of each run. method for precise elemental analysis.

The combined use of MACLAS and VORTEX provides a robust and reproducible approach for characterizing the mineralogical composition and determining the geological provenance of green phosphate beads in archaeological contexts.

6. RESULTS AND DISCUSSION  ⌅

6.1. Amber

The FTIR spectra of bead 533.6.4_6 confirm that the raw material is Baltic amber, as evidenced by the presence of the characteristic ‘Baltic shoulder’. This feature is defined by strong absorption bands at ~1160 and 1150 cm⁻¹, preceded by a horizontal band from 1250 to 1180 cm⁻¹ (Beck et al., 1964Beck, C. W., Wilbur, E. and Meret, S. (1964). “Infra-Red Spectra and the Origin of Amber”. Nature, 201 (4916), pp. 256-257. DOI: https://doi.org/10.1038/201256a0., 1965Beck, C. W., Wilbur, E., Meret, S., Kossove, D. and Kermani, K. (1965). “The Infrared Spectra of Amber and the Identification of Baltic Amber”. Archaeometry, 8 (1), pp. 96-109.; Beck, 1982Beck, C. W. (1982). “Authentication and conservation of amber: conflict of interests”. Studies in Conservation, 27 (sup1), pp. 104-107. DOI: https://doi.org/10.1179/sic.1982.27.Supplement-1.104., 1986Beck, C. W. (1986). “Spectroscopic Investigations of Amber”. Applied Spectroscopy Reviews, 22 (1), pp. 57-110. DOI: https://doi.org/10.1080/05704928608060438.), confirming a Baltic provenance (Fig. 4).

On the Iberian Peninsula, Baltic amber beads are predominantly associated with the Bronze and Iron Ages, based on radiocarbon-dated contexts (Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.). The amber bead from Bela Vista, while undated, has been tentatively linked to Bell Beaker pottery (Leisner, 1965Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter., pp. 85-87; Ferreira, 1966Ferreira, O. da V. (1966). “Os artefactos préhistóricos de ámbar e sua distribuição em Portugal”. Revista de Guimarães, 76 (1-2), pp. 61-66., p. 63). However, the excavators (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.) reported significant stratigraphic disturbance due to looting, undermining this attribution. Similar issues are present at sites like Larrarte (Beasain, Guipúzcoa) (Mujika and Armendáriz, 1991Mujika, J. A. and Armendáriz, A. (1991). “Excavaciones en la estación megalítica de Murumendi (Beasain, Gipuzkoa)”. Munibe, 43, pp. 105-165.; Álvarez Fernández et al., 2005Álvarez Fernández, E., Peñalver Mollá, E. and Delclòs Martínez, X. (2005). “La presencia de ámbar en los yacimientos prehistóricos (del Paleolítico Superior a la Edad del Bronce) de la Cornisa Cantábrica y sus fuentes de aprovisionamiento”. Zephyrus: Revista de prehistoria y arqueología, 58, pp. 159-182.), El Bosc I (L’Espunyola, Barcelona) (Serra, 1927Serra Vilaró, J. (1927). Civilitzacio megalitica a Catalunya: contribució al seu estudi. Tipografia Catalònia.; Rovira i Port, 1994Rovira i Port, J. (1994). “Ámbar y pasta vítrea. Elementos de prestigio entre el neolítico avanzado y el bronce final del nordeste de la península ibérica. Un primer estado de la cuestión”. Quaderns de Prehistòria i Arqueologia de Castelló, 16, pp. 67-91., 1996Rovira i Port, J. (1996). “Una cuenta singular vitrificada de tipo orientalizante entre los depósitos funerarios de un túmulo catalán del Bronce Medio: el monumento I de El Bosc de Correà (L’Espunyola, Berguedà, Cataluña)”. Trabajos de Prehistoria, 53 (1), pp. 155-162. DOI: https://doi.org/10.3989/tp.1996.v53.i1.411.), and Sepulcre de la Pera (Pinós, Lleida) (Castany Llusà and Guerrero Sala, 2010Castany Llusà, J. and Guerrero Sala, L. (2010). Memòria arqueològica sepulcres megalítics del Solsonès 1983-84. Barcelona: Generalitat de Catalunya, Centre d´Informació y Documentació del Patrimoni Cultural.), where amber beads were found near Bell Beaker pottery under ambiguous stratigraphic conditions.

Recent studies indicate that Bell Beaker funerary contexts in inland Iberia frequently include exotic objects, such as amber, marine shells, flint, gold, and variscite. These objects were not necessarily deposited with the same individuals, suggesting complex burial practices and structured spatial associations (Barroso et al., 2015Barroso Bermejo, R., Bueno Ramírez, P., Vázquez Cuesta, A., González Martín, A. and Peña Chocarro, L. (2015). “Enterramientos individuales y enterramientos colectivos en necrópolis del megalitismo avanzado del interior: la cueva 9 de Valle de las Higueras. Toledo”. In: Rocha, L., Bueno Ramírez, P. and Branco, G. (Eds.). Death as Archaeology of Transition: Thoughts and Materials. Papers from the II International Conference of Transition Archaeology: Death Archaeology, 29th April – 1st May 2013. BAR International Series, 2708. Oxford: Archaeopress, pp. 165-176., p. 168). However, Du Gardin (1998Du Gardin, C. (1998). “Le Campaniforme et l’ambré: mythe ou réalité?” Bulletin de la Société préhistorique française, 95 (3), pp. 343-350. DOI: https://doi.org/10.3406/bspf.1998.10809., p. 347) emphasizes the limited and highly selective use of amber, primarily in funerary contexts, with only a small fraction of Beaker-associated burials containing it. Alday Ruiz (2018)Alday Ruiz, A. (2018). “Vías de intercambio y promoción del campaniforme marítimo y mixto sobre el interior peninsular”. Cuadernos de Arqueología, 9, pp. 111-174. DOI: https://doi.org/10.15581/012.9.27774. cautions against assuming a direct link between such materials, noting that the spatial distributions of Bell Beaker pottery, amber, and variscite only partially overlap.

The presence of Baltic amber and Bell Beaker pottery at sites such as Bela Vista may be due to:

1. Different individuals being interred in shared or reused funerary spaces.
2. Stratigraphic disturbances, site reuse, or hoard depositions that displaced materials across layers.

In Larrarte, for example, a Baltic amber bead was found alongside Bell Beaker pottery, but radiocarbon dates from the tomb span 4236-1690 cal BCE⁵5 Radiocarbon dating was conducted on only six of the twelve recovered individuals. The most recently dated individual is associated with Bell Beaker pottery and an amber bead., with the final burial dated to 2289-1690 cal BCE (Mujika and Edeso, 2011Mujika, J. and Edeso, J. (2011). “Los primeros agricultores y ganaderos en Gipuzkoa del Neolítico a la Edad del Hierro”. Arkeologia 0.2. Donostia: Gipuzkoako Foru Aldundia, pp. 170-188.)⁶6 SPD of 3620 ± 60 BP, GrA-20497, Human bone, intcal20 (Reimer et al., 2020), 2 sigma, on rcarbon (Crema and Bevan, 2021)., suggesting the bead belongs to the Early Bronze Age. El Bosc I, another example, included late Bell Beaker pottery, a glass bead, and amber beads, dated to the Middle Bronze Age (Rovira i Port, 1994Rovira i Port, J. (1994). “Ámbar y pasta vítrea. Elementos de prestigio entre el neolítico avanzado y el bronce final del nordeste de la península ibérica. Un primer estado de la cuestión”. Quaderns de Prehistòria i Arqueologia de Castelló, 16, pp. 67-91., p. 82). The Baltic origin of those amber beads was recently confirmed (Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.).

At Sepulcre de la Pera, despite stratigraphic issues, the presence of Pyrenean-style Bell Beaker pottery and Baltic amber supports a Bronze Age use (~2000-1500 cal BCE) (Castany Llusà and Guerrero Sala, 2010Castany Llusà, J. and Guerrero Sala, L. (2010). Memòria arqueològica sepulcres megalítics del Solsonès 1983-84. Barcelona: Generalitat de Catalunya, Centre d´Informació y Documentació del Patrimoni Cultural., p. 29).

These cases suggest that the Bela Vista amber bead could date to the Early Bronze Age (2200-1800 BCE), overlapping with the final phases of Bell Beaker use in Portuguese Estremadura (Cardoso, 2014Cardoso, J. L. (2014). “Absolute chronology of the Beaker phenomenon North of the Tagus estuary: demographic and social implications”. Trabajos de Prehistoria, 71 (1), pp. 56-75. DOI: https://doi.org/10.3989/tp.2014.12124.). However, the presence of Iron Age materials in Level C1, such as wheel-thrown pottery and a Hallstatt-type silver bow fibula (Vilaça and Cardoso, 2017Vilaça, R. and Cardoso, J. L. (2017). “O Tejo português durante o Bronze Final”. In: Celestino Pérez, S. and Rodríguez González, E. (Eds.). Territorios comparados: los valles del Guadalquivir, el Guadiana y el Tajo en época tartésica. Anejos de Archivo Español de Arqueología, 80. Madrid: CSIC, pp. 237-281.), complicates a straightforward association.

The fibula, described by Vilaça (2006)Vilaça, R. (2006). “Artefactos de ferro em contextos do Bronze Final do território português: Novos contributos e reavaliação dos dados”. Complutum, 17, pp. 81-102., and Vilaça and Cardoso (2017)Vilaça, R. and Cardoso, J. L. (2017). “O Tejo português durante o Bronze Final”. In: Celestino Pérez, S. and Rodríguez González, E. (Eds.). Territorios comparados: los valles del Guadalquivir, el Guadiana y el Tajo en época tartésica. Anejos de Archivo Español de Arqueología, 80. Madrid: CSIC, pp. 237-281. as a double-spring fibula, lacks the typical breaks for the pin and pin-holder (Fig. 5), raising doubts about its identification.

Further evidence from Quinta do Marcelo (Setúbal), a site with no Bell Beaker pottery, strengthens an Iron Age connection. There, a Baltic amber bead was found in waste pit 2 (level 1), together with a double-spring bronze fibula and high-end artifacts (Soares and Arruda, 2017Soares, A. and Arruda, A. (2017). “A cronologia de radiocarbono para a Idade do Ferro Orientalizante no território português. Uma leitura crítica dos dados arqueométricos e arqueológicos”. In: Barceló, J. A., Bogdanovic, I. and Morrell Rovira, B. (Eds.). Iber-Crono. Actas del congreso de Cronometrías para la Historia de la Península Ibérica, Barcelona, 17-19 de octubre 2016. Barcelona: Universidad Autónoma de Barcelona, pp. 237-259., pp. 243-244). Radiocarbon dates for this context (1439-209 cal BCE) (Melo and Senna-Martínez, 2001Melo, A. and Senna-Martínez, J. C. (2001). “Agricultores e Metalurgistas, da Troca ao “Mercado”: Alguns aspectos e problemas do Bronze Final e Primeira Idade do Ferro na “Península de Lisboa”. Turres Vetaras, IV, pp. 95-118.) and associated materials support a Late Bronze to Early Iron Age attribution.

Silver fibulae are rare in pre-Roman Iberia, though not unprecedented. Examples include one from El Acebuchal (Carmona, Seville, 7^th-5^th centuries BCE) and another from a cremation at the northeast wall of Ampurias (Girona, late 6^th century BCE) (Bonsor, 1899Bonsor, G. (1899). Les colonies agricoles pré-romaines de la Vallée du Betis. Paris: Ernet Leroux., pp. 24-27; Navarro, 1970Navarro, R. (1970). Las fíbulas en Cataluña. Publicaciones eventuales 16. Barcelona: Instituto de Arqueología y Prehistoria de la Universidad de Barcelona., p. 56; Ferrer Albelda, 2014Ferrer Albelda, E. (2014). “Las fíbulas”. In: Fernández Flores, Á., Rodríguez Azogue, A., Casado Ariza, M. and Prados Pérez, E. (Eds.). La necrópolis de época tartésica de la Angorrilla, Alcalá del Río, Sevilla. Historia y geografía 271. Sevilla: Secretariado de Publicaciones de la Universidad de Sevilla, pp. 393-402., p. 395). Comparable silver fibulae are also known from Punic necropolises, such as Douïmés (Carthage, 8^th-7^th centuries BCE) (Delattre, 1897Delattre, A. L. (1897). La nécropole punique de Douïmès (a Carthage) : fouilles de 1895 et 1896. Paris.). If the Bela Vista coil is indeed a fibula, the bead may date to the 7^th-5^th centuries BCE. Alternatively, the coil could have functioned as a bead—an interpretation supported by a silver washer misidentified as a black stone bead by Pina (2019)Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555. (Fig. 6). Parallels for such silver bead assemblages come from Phoenician-Punic tombs such as Aïn Dalia Kebira (Tangier), where similar components are recorded (Blaschta et al., 2024Blaschta, D., Mederos Martín, A., Yahia, S., El Mhassani, M., Odriozola Lloret, C. P., Garrido Cordero, J. Á. and Martínez-Blanes, J. M. (2024). “The Phoenician-Punic Necropolises Djebila and Aïn Dalia Kebira (Tangier Region, Morocco)”. Madrider Mitteilungen, 65, pp. 152-199. DOI: https://doi.org/10.34780/E163-U166., p. 164, fig. 5).

In the Iberian Peninsula, a similar association between Baltic amber objects and Late Bronze/Iron Age bronze wire coil can also be observed, as in the reuse of megalithic structure of Llano de la Sabina 99 (Gorafe, Granada) (Lorrio, 2008Lorrio, A. J. (2008). Qurénima: el Bronce Final del sureste en la Península Ibérica. Madrid: Real Academia de la Historia., p. 187; Murillo-Barroso et al., 2018Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.).

Compounding the ambiguity are 15 copper-based artifacts⁷7 In addition to these 15 copper-based items, Mello et al. (1961, p. 243) document a Palmela-type arrowhead and a knife point, both of which are confidently dated to the 3^rd millennium BCE., including arc-shaped filaments, which could represent fragments of bronze rings, fibulae, or earrings (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.; Pina, 2019Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555., p. 61, fig. 181), highlighting the disturbed nature of Level C1 and strengthening the association with an Iron Age deposit.

The co-occurrence of amber and wire-coiled beads is a hallmark of elite Iron Age burials, especially in the Balkans (11^th-6^th centuries BCE) (Ivanova and Kuleff, 2009Ivanova, S. and Kuleff, I. (2009). “Archaeological Amber from the Late Bronze and Iron Ages from the Territory of Present Bulgaria”. Archaeologia Bulgarica, XIII (3), pp. 23-46., pp. 27-32). One notable example is a female burial near Gradets (Bulgaria), which included amber, bronze and silver spiral beads, and fibulae. A striking parallel from Djurslöv (Sweden) features a young woman buried with alternating amber and silver coiled beads suspended between two bronze fibulae (Lundqvist, 2018Lundqvist, K. (2018). “Glass and Amber Beads from the Late Roman Iron Age in Scania”. Lund Archaeological Review, 24-25, pp. 63-79., pp. 70-73).

These Mediterranean and European analogies suggest that the Bela Vista assemblage represents a high-status Iron Age burial, possibly influenced by Phoenician or Mediterranean trade networks. A stylistic reconstruction (Fig. 7) illustrates how the materials may have been worn—amber beads alternating with silver spirals, a cloak fastened with fibulae, and bronze earrings.

Current research indicates that the large-scale circulation of Baltic amber into Iberia did not begin until after 1200 BCE, in contrast to its earlier presence in Central Europe, the Aegean, and the British Isles (Vandkilde et al., 2024Vandkilde, H., Fischer Stephansen, C., Suchowska-Ducke, P., Ahlqvist, L., Skaaning Andersen, C., Felding, L.,… and Nørgaard, H. W. (2024). “Metal-for-Amber in the European Bronze Age”. Praehistorische Zeitschrift, 99 (1), pp. 280-338. DOI: https://doi.org/10.1515/pz-2024-2003.). The unique case of a Baltic amber bead from Cova del Frare (Matadepera, Barcelona) dated to the 4^th millennium BCE (Murillo-Barroso et al., 2023Murillo-Barroso, M., Cólliga, A. M. and Martinón-Torres, M. (2023). “The earliest Baltic amber in Western Europe”. Scientific Reports, 13 (1), 14250. DOI: https://doi.org/10.1038/s41598-023-41293-0.) is likely the result of post-depositional movement or contamination, given the implausibility of such an early date (Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.). The site also yielded an Iron Age sword and fusiform glass bead, reinforcing a Late Bronze or Iron Age context (Giró i Romeu and Masachs, 1968Giró i Romeu, P. and Masachs, J. M. (1968). “Hallazgos prehistóricos en los alrededores de La Lacuna. Castillo de Vilademager”. Empúries: revista de món clàssic i antiguitat tardana, 30, pp. 207-213.; Rafel i Fontanals, 1978Rafel i Fontanals, N. (1978). “La cueva de ‘La Roca del Frare’ en La Llacuna, Comarca del Penedés”. Pyrenae: Revista de Prehistòria i Antiguitat de la Mediterrània Occidental, 13-14, pp. 43-59.).

Therefore, while a tentative association with Bell Beaker contexts cannot be entirely excluded, the cumulative archaeological, stratigraphic, and compositional evidence, together with comparative parallels, strongly supports an Iron Age attribution for the Bela Vista amber bead.

6.2. Greenstone

Analysis via the MACLAS (Sánchez-Gómez et al., 2024Sánchez-Gómez, D., Odriozola Lloret, C. P., Sousa, A. C., Garrido-Cordero, J. Á., Romero-García, G., Martínez-Blanes, J. M.,… and Gonçalves, V. S. (2024). “A supervised multiclass framework for mineral classification of Iberian beads”. PLOS ONE, 19 (7), e0302563. DOI: https://doi.org/10.1371/journal.pone.0302563.) classified three beads as variscite (Group VII – Phosphates, Arsenates, Vanadates of Dana’s New Mineralogy; Gaines et al., 1997Gaines, R. V., Skinner, H. C. W., Foord, E. E., Mason, B. and Rosenzweig, A. (1997). Dana’s new mineralogy. 8^th ed. John Wiley & Sons Ltd.), with a probability score >97 %. One bead was classified as muscovite, a phyllosilicate from Group VIII (Silicates) (Tab. 3).

The VORTEX model (Sánchez-Gómez et al., 2025Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., García, R. V., Edo i Benaiges, M., Sousa, A. C.,… and Odriozola, C. P. (2025). “VORTEX (Variscite origin recognition technology X-ray based) Data. A European geoarchaeological green phosphate compositional dataset”. Data in Brief, 62, 111961. DOI: https://doi.org/10.1016/j.dib.2025.111961., 2026Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., García, R. V., Sousa, A. C., Vega, M. D. Z.,… and Odriozola, C. P. (2026). “A Forest of Green Beads: A Machine-Learning Based Framework to Determine the Geological Provenance of Prehistoric Variscite Artifacts”. Journal of Archaeological Science, 185: 106428. DOI: https://doi.org/10.1016/j.jas.2025.106428.) suggests that beads 533.6.4_1 and 533.6.4_5 likely originate from the Aliste region (Zamora, Spain), with ~86 % confidence, and bead 533.6.4_2 with ~70 %. This supports a Palazuelo de las Cuevas source (Villalobos García and Odriozola, 2016Villalobos García, R. and Odriozola, C. P. (2016). “Organizing the Production of Variscite Personal Ornaments in Later Prehistoric Iberia: The Mines of Aliste and the Production Sites of Quiruelas de Vidriales (Zamora, Spain)”. European Journal of Archaeology, 19 (4), pp. 631-651. DOI: https://doi.org/10.1080/14619571.2016.1147316.).

While early classifications (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.; Leisner, 1965Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter.) were mostly correct, one bead previously labeled variscite was identified as muscovite. Such mixed assemblages of phosphate, mica, and silicate beads are common. The dominance of variscite suggests long-distance exchange, underscoring Bela Vista’s significance.

The Aliste origin aligns these beads with the Bell Beaker phase (2600-1800 BCE) (Odriozola et al., 2016Odriozola, C. P., García, R. V., Burbidge, C. I., Boaventura, R., Sousa, A. C., Rodríguez-Ariza, O.,… and Dias, M. I. (2016). “Distribution and chronological framework for Iberian variscite mining and consumption at Pico Centeno, Encinasola, Spain”. Quaternary Research, 85 (1), pp. 159-176. DOI: https://doi.org/10.1016/j.yqres.2015.11.010.), supported by variscite’s declining availability in the 2^nd millennium BCE.

6.3. Amber and variscite in Iberia

Although the available evidence strongly suggests that the Baltic amber bead from Bela Vista is best attributed to the Iron Age, and that the greenstone beads are more likely associated with a late 3^rd millennium BCE (Copper Age) context, the possibility of an Early Bronze Age (ca. 2200-1800 BCE) attribution for the amber bead cannot be entirely ruled out.

Amber and variscite have been found together in numerous Iberian funerary contexts, including Campo de Hockey tomb E3-C15 (Cádiz; Vijande Vila et al., 2015Vijande Vila, E., Domínguez-Bella, S., Cantillo Duarte, J. J., Martínez López, J. and Barrena Tocino, A. (2015). “Social inequalities in the Neolithic of southern Europe: The grave goods of the Campo de Hockey necropolis (San Fernando, Cádiz, Spain)”. Comptes Rendus Palevol, 14 (2), pp. 147-161. DOI: https://doi.org/10.1016/j.crpv.2014.11.004.), Chousa Nova (Pontevedra; Domínguez Bella and Bóveda, 2011Domínguez Bella, S. and Bóveda, M. J. (2011). “Variscita y ámbar en el Neolítico gallego. Análisis arqueométrico del collar del túmulo 1 de Chousa Nova, Silleda (Pontevedra, España)”. Trabajos de Prehistoria, 68 (2), pp. 369-380. DOI: https://doi.org/10.3989/tp.2011.11075.), Dolmen de Alberite (Cádiz; Domínguez Bella, 1996Domínguez Bella, S. (1996). “Caracterización mineralógica y petrológica de algunos objetos del ajuar y de los recubrimientos de las paredes y suelos de la cámara (materiales líticos y ocres)”. In: Ramos Muñoz, J. and Giles Pacheco, F. (Eds.). El Dolmen de Alberite (Villamartín). Aportaciones a las formas económicas y sociales de las comunidades neolíticas en el noroeste de Cádiz. Cádiz: Servicio de Publicaciones de la Universidad de Cádiz, pp. 187-206.; Domínguez Bella et al., 2001Domínguez Bella, S., Rodríguez, M. and Muñoz, J. (2001). “Estudio analítico de las cuentas de collar de ámbar del dolmen de Alberite, (Villamartín, Cádiz). Naturaleza química y mineralógica e implicaciones sobre su origen”. In: Pardo Rodríguez, M. L., Gómez Tubio, B. and Respaldiza Galisteo, M. Á. (Eds.). III Congreso Nacional de Arqueometría. Sevilla: Universidad de Sevilla, pp. 621-630.), Anta da Capela (Portalegre; Odriozola et al., 2019Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7.), Anta Grande do Zambujeiro (Évora; Odriozola et al., 2012Odriozola, C. P., Mataloto, R., Moreno-García, J., Villalobos García, R. and Martínez-Blanes, J. M. (2012). “Producción y circulación de rocas verdes y sus productos en el SW peninsular: el caso de Anta Grande do Zambujeiro”. Estudos Arqueologicos de Oeiras, 19, pp. 125-142., 2019Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7.), Anta Grande da Comenda da Igreja (Évora; Leisner, 1965Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter.), Anta dos Penedos de São Miguel (Portalegre; Claustre et al., 2005Claustre, F., Gonçalves, V., Arruda, A. and Zammit, J. (2005). “Le dolmen Os Penedos de São Miguel, Crato, Alto Alentejo, Portugal”. In: Martzluff, M. (Ed.). Roches ornées, roches dressées. Perpignan : Presses universitaires de Perpignan, pp. 119-138.), Alcalar tombs 3 and 4 (Faro; Sousa et al., 2024Sousa, A. C., Garrido-Cordero, J. Á. and Odriozola, C. P. (2024). “A circulação de matérias exóticas no Extremo Sul do Ocidente Peninsular durante os 4.^o e 3.^o milénios a.n.e.: alguns contributos e muitas questões em aberto”. In: Sousa, A. C. (Ed.). Fogo e Morte. Sobre o Extremo Sul no 3o milénio a.n.e. Estudos oferecidos a Victor S. Gonçalves nos 30 anos da edição de Megalitismo e Metalurgia no Alto Algarve Oriental, uma aproximação integrada. Terra & Tempo. Estudos do Museu Municipal de Loulé 1. Loulé: Câmara Municipal de Loulé, pp. 399-438.), São Paulo 2 (Setúbal; Barros and Espíritu Santo, 1997Barros, L. and Espíritu Santo, P. (1997). “Gruta artificial de São Paulo”. Setúbal Arqueológica, 11-12, pp. 217-220.), Las Arnillas (Burgos; Villalobos García, 2016Villalobos García, R. (2016). Análisis de las transformaciones sociales en la Prehistoria Reciente de la Meseta Norte española (milenios VI-III cal a.C.). PhD Thesis. Universidad de Valladolid. Available at: https://uvadoc.uva.es/handle/10324/16693.), La Velilla (Palencia; Villalobos García, 2016Villalobos García, R. (2016). Análisis de las transformaciones sociales en la Prehistoria Reciente de la Meseta Norte española (milenios VI-III cal a.C.). PhD Thesis. Universidad de Valladolid. Available at: https://uvadoc.uva.es/handle/10324/16693.), Errekatxuetako Atxa (Bizkaia; López Quintana, 2015López Quintana, J. C. (2015). “Dólmenes, cistas y menhires en la estación megalítica de Gorbeia (País Vasco): distribución geográfica y secuencia funeraria”. In: Rocha, L., Bueno-Ramírez, P. and Branco, G. (Eds.). Death as Archaeology of Transition: Thoughts and Materials. Papers from the II International Conference of Transition Archaeology: Death Archaeology, 29th April – 1st May 2013. BAR International Series, 2708. Oxford, Archaeopress, pp. 197-219.), Trikuaitzi I (Guipúzcoa; Mujika and Armendáriz, 1991Mujika, J. A. and Armendáriz, A. (1991). “Excavaciones en la estación megalítica de Murumendi (Beasain, Gipuzkoa)”. Munibe, 43, pp. 105-165.), Cova de la Pastora (Alicante; García-Puchol et al., 2012García-Puchol, O., McClure, S. B., Juan Cabanilles, J., Pascual-Benito, J. L. and Gibaja, J. F. (2012). “Objetos singulares/objetos foráneos. Evidencias de circulación de artesanías en el depósito funerario del Neolítico Final/Calcolítico de la Cova de la Pastora (Alcoi, Alacant)”. Rubricatum: revista del Museu de Gavà, 5, pp. 281-288.), Cal Rajolí (Lleida; Serra, 1927Serra Vilaró, J. (1927). Civilitzacio megalitica a Catalunya: contribució al seu estudi. Tipografia Catalònia.), tholos de la Pastora (Seville; Almagro, 1962Almagro, M. (1962). “El ajuar del Dolmen de La Pastora de Valentina del Alcor (Sevilla). Sus paralelos y su cronología”. Trabajos de Prehistoria, 5, pp. 5-38.; Murillo-Barroso et al., 2018Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.), Perdigões tomb 1 and tomb 2 (Reguengos de Monsaraz; Odriozola et al., 2010Odriozola, C. P., Linares Catela, J. A. and Hurtado, V. (2010). “Perdigões green beads provenance analysis”. Apontamentos de Arqueologia e Patrimonio, 6, pp. 47-51.; Valera, 2017Valera, A. C. (2017). “The ‘Exogenous’ at Perdigões. Approaching Interaction in the Late 4^th and 3^rd Millennium BC in Southwest Iberia”. In: Bartelheim, M., Bueno Ramírez, P. and Kunst, M. (Coords.). Key Resources and Sociocultural Developments in the Iberian Chalcolithic. Ressourcen Kulturen 6. Tübingen: Tübingen Library Publishing, pp. 201-224.), and Valle de las Higueras 1 and 3 (Toledo; Barroso et al., 2021Barroso Bermejo, R., Odriozola, C. P., Bueno Ramírez, P., Villalobos García, R., Balbín Behrmann, R. and Martínez Blanes, J. M. (2021). “Mineral adornments at Chalcolithic sites in inland Iberia: variscite beads at Valle de las Higueras (Huecas, Toledo) Spain”. Mediterranean Archaeology and Archaeometry, 21 (3), pp. 177-203. DOI: https://doi.org/10.5281/zenodo.5598231.).

While these associations confirm that amber and variscite could form part of the same burial assemblages, analytical studies consistently indicate that the amber found at these sites is not of Baltic origin. This significantly reduces the likelihood that variscite was ever associated with Baltic amber in prehistoric Iberian contexts, making such a combination—like that proposed for Bela Vista—highly improbable.

The Baltic origin of the Bela Vista bead therefore aligns more convincingly with an Iron Age chronology. The absence of variscite in Iberian sites with confirmed Baltic amber further reinforces this interpretation and diminishes the plausibility of an Early Bronze Age context for the Bela Vista bead.

Moreover, the scarcity of Baltic amber in pre-Bronze Age Iberian contexts remains a major challenge to such an attribution. As previously discussed, the large-scale introduction of Baltic amber into the Iberian Peninsula only began after ca. 1200 BCE, during the Late Bronze Age (Vandkilde et al., 2024Vandkilde, H., Fischer Stephansen, C., Suchowska-Ducke, P., Ahlqvist, L., Skaaning Andersen, C., Felding, L.,… and Nørgaard, H. W. (2024). “Metal-for-Amber in the European Bronze Age”. Praehistorische Zeitschrift, 99 (1), pp. 280-338. DOI: https://doi.org/10.1515/pz-2024-2003.). The exceptional case of a Baltic amber bead from Cova del Frare, dated to the 4^th millennium BCE (Murillo-Barroso et al., 2023Murillo-Barroso, M., Cólliga, A. M. and Martinón-Torres, M. (2023). “The earliest Baltic amber in Western Europe”. Scientific Reports, 13 (1), 14250. DOI: https://doi.org/10.1038/s41598-023-41293-0.), remains an anomaly and is likely the result of post-depositional disturbance or contamination. The same site also yielded Iron Age materials, including a sword and a fusiform glass bead, further supporting a later chronological framework (Giró i Romeu and Masachs, 1968Giró i Romeu, P. and Masachs, J. M. (1968). “Hallazgos prehistóricos en los alrededores de La Lacuna. Castillo de Vilademager”. Empúries: revista de món clàssic i antiguitat tardana, 30, pp. 207-213.; Rafel i Fontanals, 1978Rafel i Fontanals, N. (1978). “La cueva de ‘La Roca del Frare’ en La Llacuna, Comarca del Penedés”. Pyrenae: Revista de Prehistòria i Antiguitat de la Mediterrània Occidental, 13-14, pp. 43-59.; Murillo-Barroso et al., 2023Murillo-Barroso, M., Cólliga, A. M. and Martinón-Torres, M. (2023). “The earliest Baltic amber in Western Europe”. Scientific Reports, 13 (1), 14250. DOI: https://doi.org/10.1038/s41598-023-41293-0.).

That said, an Early Bronze Age attribution for the Bela Vista bead cannot be categorically ruled out. If the bead was indeed deposited during this period, it would represent a rare—though not unprecedented—instance of Baltic amber reaching western Iberia via long-distance exchange networks linking the Baltic region to Central Europe and, indirectly, to the Iberian Peninsula. This trend can be observed, for instance, in the prestigious burials at Horta do Pinheiro 5 (Torrão do Alentejo), which contain ivory and silver (Monge et al., 2021Monge Soares, A. M., Melo, L., Valério, P., Silva, A. M., Pais Martins, P., Monge Soares, R. M. G.,… and Silva, R. J. C. (2021). “Símbolos de estatus o una visión de los primeros momentos del Bronce Medio del suroeste: las estructuras funerarias de Horta do Pinheiro 5 (Torrão do Alentejo, sur de Portugal)”. Trabajos de Prehistoria, 78 (2), pp. 292-308. DOI: https://doi.org/10.3989/tp.2021.12277.).

The discovery of a complete amber necklace at Cabecinho da Capitôa (Sousa et al., 2022Sousa, A. C., Pereira, C., Miranda, M., Monge Soares, A., Odriozola, C. P. and Arruda, A. M. (2022). “Cabecinho da Capitôa (Mafra, Lisbon, Portugal). An Amber Necklace and Ceramic Vessels in Votive Contexts of the Western Iberian Late Bronze Age/Early Iron Age”. Madrider Mitteilungen, 63, pp. 42-75. DOI: https://doi.org/10.34780/99co-kc98.), located on the northern platform of the Serra de Sintra very close to Bela Vista, is also noteworthy. This find has been radiocarbon dated to the 8^th and 6^th centuries BCE (Sousa et al., 2022Sousa, A. C., Pereira, C., Miranda, M., Monge Soares, A., Odriozola, C. P. and Arruda, A. M. (2022). “Cabecinho da Capitôa (Mafra, Lisbon, Portugal). An Amber Necklace and Ceramic Vessels in Votive Contexts of the Western Iberian Late Bronze Age/Early Iron Age”. Madrider Mitteilungen, 63, pp. 42-75. DOI: https://doi.org/10.34780/99co-kc98.). As with other deposits—such as the Iron Age hoard from Palacio III (Almadén de la Plata, Seville; Murillo-Barroso and Martinón-Torres, 2012Murillo-Barroso, M. and Martinón-Torres, M. (2012). “Amber Sources and Trade in the Prehistory of the Iberian Peninsula”. European Journal of Archaeology, 15 (2), pp. 187-216. DOI: https://doi.org/10.1179/1461957112y.0000000009.)—this assemblage does not appear to have served a funerary purpose.

Based on the current archaeological, stratigraphic, and compositional evidence, we propose that the variscite beads from Bela Vista are most plausibly associated with a Copper Age burial, in keeping with broader Iberian patterns of variscite use and circulation during the 3^rd millennium BCE. In contrast, the Baltic amber bead and associated silver wire coil are more credibly linked to an Iron Age burial, most likely dating to the 7^th-5^th centuries BCE. This interpretation is supported by regional patterns of Baltic amber consumption during the Iron Age, the typological features of the associated artifacts, and the complex stratigraphy of the Bela Vista tholos.

While a tentative Early Bronze Age attribution for the amber bead remains theoretically conceivable—especially given that the Beaker horizon extended into the early 2^nd millennium BCE and that Baltic amber exchange had already begun in northwestern Europe—we consider this scenario less likely. The presence of Iron Age materials in the same stratigraphic layer, the extreme rarity of pre-Bronze Age Baltic amber in Iberia, and the contextual and typological parallels all favor an Iron Age attribution.

7. CONCLUSIONS  ⌅

Our examination of personal adornment materials has enabled the reintegration into scholarly discourse of the amber bead from the Bela Vista tholos, which had remained unaccounted for over six decades. Through FTIR analysis, we have confirmed its Baltic origin. This, coupled with its association with a silver artifact, provides strong support for an Iron Age chronology (7^th-5^th centuries BCE).

The Baltic amber bead from Bela Vista must be understood within two key contextual frameworks: the near-total absence of Baltic amber in pre-Bronze Age Iberia, and its association with silver, a material rarely found in prehistoric funerary contexts in Portugal. While amber is present in Copper Age and Bell Beaker contexts, it is exclusively of Sicilian origin (Murillo-Barroso et al., 2018Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.; Odriozola et al., 2019Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7.). Notably, no association exists between Baltic amber and either Bell Beaker vessels or variscite beads in Iberian archaeological contexts. In all documented cases where variscite co-occurs with amber, the latter is Sicilian—never Baltic.

The analytical results presented here, particularly the FTIR identification of Baltic amber and the associated silver coil, further support an Iron Age attribution. This aligns with the emergence of Baltic amber in Iberian contexts ca. 1200 BCE (Vandkilde et al., 2024Vandkilde, H., Fischer Stephansen, C., Suchowska-Ducke, P., Ahlqvist, L., Skaaning Andersen, C., Felding, L.,… and Nørgaard, H. W. (2024). “Metal-for-Amber in the European Bronze Age”. Praehistorische Zeitschrift, 99 (1), pp. 280-338. DOI: https://doi.org/10.1515/pz-2024-2003.) and with parallels from Iron Age votive deposits, such as those documented at Palacio III (Murillo-Barroso and Martinón-Torres, 2012Murillo-Barroso, M. and Martinón-Torres, M. (2012). “Amber Sources and Trade in the Prehistory of the Iberian Peninsula”. European Journal of Archaeology, 15 (2), pp. 187-216. DOI: https://doi.org/10.1179/1461957112y.0000000009.), Llano de la Sabina 99 (Murillo-Barroso et al., 2018Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.), Cova del Llidoner (Alicante) and Correio-Mor cave (Lisboa; Garrido-Cordero et al., 2024Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.), where later materials were introduced into earlier megalithic contexts.

We propose that the Bela Vista megalithic tomb was reused during the Iron Age for a high-status funerary deposit, which included a Baltic amber bead, a silver wire-coil, and other bronze objects—likely personal adornments. This secondary use is consistent with a broader pattern of monument reuse in Iberia, where prehistoric tombs were reappropriated for elite burials or ritual depositions in later periods (Lorrio, 2008Lorrio, A. J. (2008). Qurénima: el Bronce Final del sureste en la Península Ibérica. Madrid: Real Academia de la Historia.).

At the same time, the presence of Bell Beaker pottery, Palmela points, and V-perforated buttons, in the primary assemblage confirms the site’s main use during the second half of the 3^rd millennium BCE. An earlier Copper Age phase may also be inferred from the presence of copos canelados, which were identified by Pina (2019)Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555. but largely overlooked in earlier publications. These objects suggest a funerary phase, potentially linked to long-distance exchange networks that brought exotic materials such as variscite into the region. However, the limited contextual information in excavation records and museum catalogues hinders a full reconstruction of the original burial sequence.

One of the most significant outcomes of this research is the reidentification of a set of silver disc-shaped beads, previously interpreted as part of a fibula coil. Their morphology, contextual association, and typological features strongly suggest their use as independent ornamental elements. This finding represents a novel contribution to the archaeological record of Portugal, as such items had not been previously documented in Iron Age contexts within the region. Their presence reinforces the interpretation of the Bela Vista tholos as a site of high-status reuse during the Orientalizing period.

Ultimately, this study highlights the value of applying modern analytical techniques to legacy collections. The rediscovery and reclassification of the amber bead—previously thought lost and misidentified—demonstrate the potential of reexamining museum holdings to yield new archaeological insights. The integration of archaeometry with contextual and typological data has clarified the multi-period use of the Bela Vista monument and refined our understanding of long-distance exchange and symbolic practices in prehistoric Iberia.

SUPPLEMENTARY FILES  ⌅

The following supplementary material is available on the journal’s website: SF1. Coordinates and details of the sites mentioned in the text.

ACKNOWLEDGEMENTS  ⌅

We extend our deepest gratitude to the Museu dos Serviços Geológicos de Lisboa, and particularly to José Anacleto, whose unwavering professionalism, scholarly generosity, and profound expertise in Iberian collections were instrumental to this study. His dedication to preserving and contextualizing archaeological materials sets a benchmark for the field.

We are equally indebted to our colleagues for their invaluable insights during the development of this manuscript: D. Blaschta, E. Ferrer Albelda, and J. A. Mujika Alustiza. Their collective wisdom greatly enriched this work. Any errors or omissions remain solely the responsibility of the authors.

We also wish to thank the anonymous reviewers for their thoughtful and constructive feedback, which substantially improved the clarity, depth, and overall quality of this paper.

DECLARATION OF COMPETING INTEREST  ⌅

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

FUNDING SOURCES  ⌅

This research was funded by the Ministerio de Ciencia e Innovación through the project “Arqueología de las falsificaciones y la percepción: adornos y autopercepción en el Mediterráneo occidental” (Ref. PID2021-124421NB-I00). Daniel Sánchez-Gómez acknowledges support from the Fundação para a Ciência e a Tecnologia through a PhD grant (Ref. 753886).

AUTHORSHIP CONTRIBUTION STATEMENT  ⌅

José Ángel Garrido-Cordero: conceptualization, data curation, formal analysis, investigation, writing – original draft, writing – review & editing.

Rita Loureiro: investigation.

José María Martínez-Blanes: formal analysis, investigation, methodology, validation, writing – review & editing.

Ana C. Sousa: writing – review & editing.

María Dolores Zambrana-Vega: investigation.

Luz Marina Salas Acosta: visualization.

Daniel Sánchez-Gómez: investigation.

Carlos P. Odriozola: conceptualization, data curation, formal analysis, funding acquisition, investigation, methodology, project administration, resources, supervision, validation, writing – original draft, writing – review & editing.

BIBLIOGRAPHY  ⌅

Alday Ruiz, A. (2018). “Vías de intercambio y promoción del campaniforme marítimo y mixto sobre el interior peninsular”. Cuadernos de Arqueología, 9, pp. 111-174. DOI: https://doi.org/10.15581/012.9.27774.

Almagro, M. (1962). “El ajuar del Dolmen de La Pastora de Valentina del Alcor (Sevilla). Sus paralelos y su cronología”. Trabajos de Prehistoria, 5, pp. 5-38.

Álvarez Fernández, E., Peñalver Mollá, E. and Delclòs Martínez, X. (2005). “La presencia de ámbar en los yacimientos prehistóricos (del Paleolítico Superior a la Edad del Bronce) de la Cornisa Cantábrica y sus fuentes de aprovisionamiento”. Zephyrus: Revista de prehistoria y arqueología, 58, pp. 159-182.

Angelini, I. and Bellintani, P. (2005). “Archaeological ambers from northern Italy: an FTIR–drift study of provenance by comparison with the geological amber database”. Archaeometry, 47 (2), pp. 441-454. DOI: https://doi.org/10.1111/j.1475-4754.2005.00212.x.

Barros, L. and Espíritu Santo, P. (1997). “Gruta artificial de São Paulo”. Setúbal Arqueológica, 11-12, pp. 217-220.

Barroso Bermejo, R., Bueno Ramírez, P., Vázquez Cuesta, A., González Martín, A. and Peña Chocarro, L. (2015). “Enterramientos individuales y enterramientos colectivos en necrópolis del megalitismo avanzado del interior: la cueva 9 de Valle de las Higueras. Toledo”. In: Rocha, L., Bueno Ramírez, P. and Branco, G. (Eds.). Death as Archaeology of Transition: Thoughts and Materials. Papers from the II International Conference of Transition Archaeology: Death Archaeology, 29th April – 1st May 2013. BAR International Series, 2708. Oxford: Archaeopress, pp. 165-176.

Barroso Bermejo, R., Odriozola, C. P., Bueno Ramírez, P., Villalobos García, R., Balbín Behrmann, R. and Martínez Blanes, J. M. (2021). “Mineral adornments at Chalcolithic sites in inland Iberia: variscite beads at Valle de las Higueras (Huecas, Toledo) Spain”. Mediterranean Archaeology and Archaeometry, 21 (3), pp. 177-203. DOI: https://doi.org/10.5281/zenodo.5598231.

Beck, C. W. (1982). “Authentication and conservation of amber: conflict of interests”. Studies in Conservation, 27 (sup1), pp. 104-107. DOI: https://doi.org/10.1179/sic.1982.27.Supplement-1.104.

Beck, C. W. (1986). “Spectroscopic Investigations of Amber”. Applied Spectroscopy Reviews, 22 (1), pp. 57-110. DOI: https://doi.org/10.1080/05704928608060438.

Beck, C. W. and Hartnett, H. E. (1993). “Sicilian amber”. In: Beck, C. W. and Bouzek, J. (Eds.). Proc. 2nd Int. Conf. Amber in Archaeology. Liblice. 1990. Prague: Czech Academy of Sciences, pp. 36-47.

Beck, C. W., Wilbur, E. and Meret, S. (1964). “Infra-Red Spectra and the Origin of Amber”. Nature, 201 (4916), pp. 256-257. DOI: https://doi.org/10.1038/201256a0.

Beck, C. W., Wilbur, E., Meret, S., Kossove, D. and Kermani, K. (1965). “The Infrared Spectra of Amber and the Identification of Baltic Amber”. Archaeometry, 8 (1), pp. 96-109.

Beck, H. C. (1928). “I. Classification and Nomenclature of Beads and Pendants”. Archaeologia (Second Series), 77, pp. 1-76. DOI: https://doi.org/10.1017/S0261340900013345.

Blaschta, D., Mederos Martín, A., Yahia, S., El Mhassani, M., Odriozola Lloret, C. P., Garrido Cordero, J. Á. and Martínez-Blanes, J. M. (2024). “The Phoenician-Punic Necropolises Djebila and Aïn Dalia Kebira (Tangier Region, Morocco)”. Madrider Mitteilungen, 65, pp. 152-199. DOI: https://doi.org/10.34780/E163-U166.

Boaventura, R. (2009). As antas e o Megalitismo da região de Lisboa. Ph.D. Thesis, Universidade de Lisboa. Facultade de Letras, Departamento de História. Available at: http://repositorio.ul.pt/handle/10451/587 (accessed September 9, 2014).

Bonsor, G. (1899). Les colonies agricoles pré-romaines de la Vallée du Betis. Paris: Ernet Leroux.

Cardoso, J. L. (2014). “Absolute chronology of the Beaker phenomenon North of the Tagus estuary: demographic and social implications”. Trabajos de Prehistoria, 71 (1), pp. 56-75. DOI: https://doi.org/10.3989/tp.2014.12124.

Castany Llusà, J. and Guerrero Sala, L. (2010). Memòria arqueològica sepulcres megalítics del Solsonès 1983-84. Barcelona: Generalitat de Catalunya, Centre d´Informació y Documentació del Patrimoni Cultural.

Claustre, F., Gonçalves, V., Arruda, A. and Zammit, J. (2005). “Le dolmen Os Penedos de São Miguel, Crato, Alto Alentejo, Portugal”. In: Martzluff, M. (Ed.). Roches ornées, roches dressées. Perpignan : Presses universitaires de Perpignan, pp. 119-138.

Crema, E. and Bevan, A. (2021). “Inference from large sets of radiocarbon dates: software and methods”. Radiocarbon, 63, pp. 23-39. DOI: https://doi.org/10.1017/RDC.2020.95.

Delattre, A. L. (1897). La nécropole punique de Douïmès (a Carthage) : fouilles de 1895 et 1896. Paris.

Domínguez Bella, S. (1996). “Caracterización mineralógica y petrológica de algunos objetos del ajuar y de los recubrimientos de las paredes y suelos de la cámara (materiales líticos y ocres)”. In: Ramos Muñoz, J. and Giles Pacheco, F. (Eds.). El Dolmen de Alberite (Villamartín). Aportaciones a las formas económicas y sociales de las comunidades neolíticas en el noroeste de Cádiz. Cádiz: Servicio de Publicaciones de la Universidad de Cádiz, pp. 187-206.

Domínguez Bella, S. and Bóveda, M. J. (2011). “Variscita y ámbar en el Neolítico gallego. Análisis arqueométrico del collar del túmulo 1 de Chousa Nova, Silleda (Pontevedra, España)”. Trabajos de Prehistoria, 68 (2), pp. 369-380. DOI: https://doi.org/10.3989/tp.2011.11075.

Domínguez Bella, S., Rodríguez, M. and Muñoz, J. (2001). “Estudio analítico de las cuentas de collar de ámbar del dolmen de Alberite, (Villamartín, Cádiz). Naturaleza química y mineralógica e implicaciones sobre su origen”. In: Pardo Rodríguez, M. L., Gómez Tubio, B. and Respaldiza Galisteo, M. Á. (Eds.). III Congreso Nacional de Arqueometría. Sevilla: Universidad de Sevilla, pp. 621-630.

Du Gardin, C. (1998). “Le Campaniforme et l’ambré: mythe ou réalité?” Bulletin de la Société préhistorique française, 95 (3), pp. 343-350. DOI: https://doi.org/10.3406/bspf.1998.10809.

Ferreira, O. da V. (1966). “Os artefactos préhistóricos de ámbar e sua distribuição em Portugal”. Revista de Guimarães, 76 (1-2), pp. 61-66.

Ferrer Albelda, E. (2014). “Las fíbulas”. In: Fernández Flores, Á., Rodríguez Azogue, A., Casado Ariza, M. and Prados Pérez, E. (Eds.). La necrópolis de época tartésica de la Angorrilla, Alcalá del Río, Sevilla. Historia y geografía 271. Sevilla: Secretariado de Publicaciones de la Universidad de Sevilla, pp. 393-402.

Gaines, R. V., Skinner, H. C. W., Foord, E. E., Mason, B. and Rosenzweig, A. (1997). Dana’s new mineralogy. 8^th ed. John Wiley & Sons Ltd.

García-Puchol, O., McClure, S. B., Juan Cabanilles, J., Pascual-Benito, J. L. and Gibaja, J. F. (2012). “Objetos singulares/objetos foráneos. Evidencias de circulación de artesanías en el depósito funerario del Neolítico Final/Calcolítico de la Cova de la Pastora (Alcoi, Alacant)”. Rubricatum: revista del Museu de Gavà, 5, pp. 281-288.

Garrido-Cordero, J. A., Odriozola, C. P., Sousa, A. C., Romero-García, G., Sánchez-Gómez, D., Martínez-Blanes, J. M.,… and Gonçalves, V. (2024). “Amber provenance as a Chrono-Cultural Proxy: Insights from FTIR analysis in the Iberian Peninsula”. Journal of Archaeological Science: Reports, 57, 104647. DOI: https://doi.org/10.1016/j.jasrep.2024.104647.

Giró i Romeu, P. and Masachs, J. M. (1968). “Hallazgos prehistóricos en los alrededores de La Lacuna. Castillo de Vilademager”. Empúries: revista de món clàssic i antiguitat tardana, 30, pp. 207-213.

Ivanova, S. and Kuleff, I. (2009). “Archaeological Amber from the Late Bronze and Iron Ages from the Territory of Present Bulgaria”. Archaeologia Bulgarica, XIII (3), pp. 23-46.

Leisner, V. (1965). Die Megalithgraber der Iberischen Halbinsel Der Western. 3. Lieferung. Berlin, Walter de Gruyter.

López Quintana, J. C. (2015). “Dólmenes, cistas y menhires en la estación megalítica de Gorbeia (País Vasco): distribución geográfica y secuencia funeraria”. In: Rocha, L., Bueno-Ramírez, P. and Branco, G. (Eds.). Death as Archaeology of Transition: Thoughts and Materials. Papers from the II International Conference of Transition Archaeology: Death Archaeology, 29th April – 1st May 2013. BAR International Series, 2708. Oxford, Archaeopress, pp. 197-219.

Lorrio, A. J. (2008). Qurénima: el Bronce Final del sureste en la Península Ibérica. Madrid: Real Academia de la Historia.

Lundqvist, K. (2018). “Glass and Amber Beads from the Late Roman Iron Age in Scania”. Lund Archaeological Review, 24-25, pp. 63-79.

Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249.

Melo, A. and Senna-Martínez, J. C. (2001). “Agricultores e Metalurgistas, da Troca ao “Mercado”: Alguns aspectos e problemas do Bronze Final e Primeira Idade do Ferro na “Península de Lisboa”. Turres Vetaras, IV, pp. 95-118.

Monge Soares, A. M., Melo, L., Valério, P., Silva, A. M., Pais Martins, P., Monge Soares, R. M. G.,… and Silva, R. J. C. (2021). “Símbolos de estatus o una visión de los primeros momentos del Bronce Medio del suroeste: las estructuras funerarias de Horta do Pinheiro 5 (Torrão do Alentejo, sur de Portugal)”. Trabajos de Prehistoria, 78 (2), pp. 292-308. DOI: https://doi.org/10.3989/tp.2021.12277.

Mujika, J. A. and Armendáriz, A. (1991). “Excavaciones en la estación megalítica de Murumendi (Beasain, Gipuzkoa)”. Munibe, 43, pp. 105-165.

Mujika, J. and Edeso, J. (2011). “Los primeros agricultores y ganaderos en Gipuzkoa del Neolítico a la Edad del Hierro”. Arkeologia 0.2. Donostia: Gipuzkoako Foru Aldundia, pp. 170-188.

Murillo-Barroso, M., Cólliga, A. M. and Martinón-Torres, M. (2023). “The earliest Baltic amber in Western Europe”. Scientific Reports, 13 (1), 14250. DOI: https://doi.org/10.1038/s41598-023-41293-0.

Murillo-Barroso, M. and Martinón-Torres, M. (2012). “Amber Sources and Trade in the Prehistory of the Iberian Peninsula”. European Journal of Archaeology, 15 (2), pp. 187-216. DOI: https://doi.org/10.1179/1461957112y.0000000009.

Murillo-Barroso, M., Peñalver, E., Bueno, P., Barroso, R., Balbín, R. de, and Martinón-Torres, M. (2018). “Amber in prehistoric Iberia: New data and a review”. PLOS ONE, 13 (8), e0202235. DOI: https://doi.org/10.1371/journal.pone.0202235.

Navarro, R. (1970). Las fíbulas en Cataluña. Publicaciones eventuales 16. Barcelona: Instituto de Arqueología y Prehistoria de la Universidad de Barcelona.

Odriozola, C. P., García, R. V., Burbidge, C. I., Boaventura, R., Sousa, A. C., Rodríguez-Ariza, O.,… and Dias, M. I. (2016). “Distribution and chronological framework for Iberian variscite mining and consumption at Pico Centeno, Encinasola, Spain”. Quaternary Research, 85 (1), pp. 159-176. DOI: https://doi.org/10.1016/j.yqres.2015.11.010.

Odriozola, C. P., Garrido-Cordero, J. Á., Santos, C., Barradas, E. and Sousa, A. C. (2020). “The stone beads from Barrada’s hypogeum 1 (Aljezur, Algarve, Portugal). Greenstone distribution patterns in the Iberian Southwest late Neolithic”. Journal of Archaeological Science: Reports, 34, 102667. DOI: https://doi.org/10.1016/j.jasrep.2020.102667.

Odriozola, C. P., Linares Catela, J. A. and Hurtado, V. (2010). “Perdigões green beads provenance analysis”. Apontamentos de Arqueologia e Patrimonio, 6, pp. 47-51.

Odriozola, C. P., Mataloto, R., Moreno-García, J., Villalobos García, R. and Martínez-Blanes, J. M. (2012). “Producción y circulación de rocas verdes y sus productos en el SW peninsular: el caso de Anta Grande do Zambujeiro”. Estudos Arqueologicos de Oeiras, 19, pp. 125-142.

Odriozola, C. P., Sousa, A. C., Mataloto, R., Boaventura, R., Andrade, M., Villalobos García, R.,… and Riquelme, J. A. (2019). “Amber, beads and social interaction in the Late Prehistory of the Iberian Peninsula: an update”. Archaeological and Anthropological Sciences, 11 (2), pp. 567-595. DOI: https://doi.org/10.1007/s12520-017-0549-7.

Peñalver, E., Álvarez-Fernández, E., Arias, P., Delclòs, X. and Ontañón, R. (2007). “Local amber in a Palaeolithic context in Cantabrian Spain: the case of La Garma A”. Journal of Archaeological Science, 34 (6), pp. 843-849. DOI: https://doi.org/10.1016/j.jas.2006.03.006.

Peñalver, E. and Delclòs, X. (2010). “Spanish amber”. In: Penney, D. (Ed.). Biodiversity of fossils in amber from the major world deposits. Manchester: Siri Scientific Press, pp. 236-270.

Pina, R. P. G. (2019). O monumento megalítico da Bela Vista (Colares, Sintra): Um contributo para o conhecimento das práticas funerárias do 3o milénio a.n.e. Volume II. MPhil Thesis. Universidade de Lisboa. Available at: http://hdl.handle.net/10451/42555.

Rafel i Fontanals, N. (1978). “La cueva de ‘La Roca del Frare’ en La Llacuna, Comarca del Penedés”. Pyrenae: Revista de Prehistòria i Antiguitat de la Mediterrània Occidental, 13-14, pp. 43-59.

Reimer, P. J., Austin, W. E., Bard, E., Bayliss, A., Blackwell, P. G., Ramsey, C. B.,… and Friedrich, M. (2020). “The IntCal20 Northern Hemisphere radiocarbon age calibration curve (0–55 cal kBP)”. Radiocarbon, 62 (4), pp. 725-757. DOI: https://doi.org/10.1017/rdc.2020.41.

Romero-García, G., Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., Sousa, A. C. and Odriozola, C. P. (2024). “Unlocking archaeological data online via the PEPAdb (Prehistoric Europe’s Personal Adornment Database) initiative for Open Science”. Antiquity, 98 (398), pp. 1-6. DOI: https://doi.org/10.15184/aqy.2024.2.

Rovira i Port, J. (1994). “Ámbar y pasta vítrea. Elementos de prestigio entre el neolítico avanzado y el bronce final del nordeste de la península ibérica. Un primer estado de la cuestión”. Quaderns de Prehistòria i Arqueologia de Castelló, 16, pp. 67-91.

Rovira i Port, J. (1996). “Una cuenta singular vitrificada de tipo orientalizante entre los depósitos funerarios de un túmulo catalán del Bronce Medio: el monumento I de El Bosc de Correà (L’Espunyola, Berguedà, Cataluña)”. Trabajos de Prehistoria, 53 (1), pp. 155-162. DOI: https://doi.org/10.3989/tp.1996.v53.i1.411.

Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., García, R. V., Edo i Benaiges, M., Sousa, A. C.,… and Odriozola, C. P. (2025). “VORTEX (Variscite origin recognition technology X-ray based) Data. A European geoarchaeological green phosphate compositional dataset”. Data in Brief, 62, 111961. DOI: https://doi.org/10.1016/j.dib.2025.111961.

Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., Villalobos García, R., Edo i Benaiges, M., Sousa, A. C.,… and Odriozola, C. P. (2026). “A Forest of Green Beads: A Machine-Learning Based Framework to Determine the Geological Provenance of Prehistoric Variscite Artifacts”. Journal of Archaeological Science, 185: 106428. DOI: https://doi.org/10.1016/j.jas.2025.106428.

Sánchez-Gómez, D., Odriozola Lloret, C. P., Sousa, A. C., Garrido-Cordero, J. Á., Romero-García, G., Martínez-Blanes, J. M.,… and Gonçalves, V. S. (2024). “A supervised multiclass framework for mineral classification of Iberian beads”. PLOS ONE, 19 (7), e0302563. DOI: https://doi.org/10.1371/journal.pone.0302563.

Serra Vilaró, J. (1927). Civilitzacio megalitica a Catalunya: contribució al seu estudi. Tipografia Catalònia.

Soares, A. and Arruda, A. (2017). “A cronologia de radiocarbono para a Idade do Ferro Orientalizante no território português. Uma leitura crítica dos dados arqueométricos e arqueológicos”. In: Barceló, J. A., Bogdanovic, I. and Morrell Rovira, B. (Eds.). Iber-Crono. Actas del congreso de Cronometrías para la Historia de la Península Ibérica, Barcelona, 17-19 de octubre 2016. Barcelona: Universidad Autónoma de Barcelona, pp. 237-259.

Sousa, A. C. (2016). “Megalitismo e Metalurgia. Os Tholoi do Centro e Sul de Portugal”. In: Sousa, A. C., Carvalho, C. and Viegas, C. (Eds.). Terra e Água. Escolher sementes, invocar a Deusa. Estudos em Homenagem a Victor S. Gonçalves. Estudos e Memórias 9. Lisboa, UNIARQ-FLUL, pp. 209-241.

Sousa, A. C., Garrido-Cordero, J. Á. and Odriozola, C. P. (2024). “A circulação de matérias exóticas no Extremo Sul do Ocidente Peninsular durante os 4.^o e 3.^o milénios a.n.e.: alguns contributos e muitas questões em aberto”. In: Sousa, A. C. (Ed.). Fogo e Morte. Sobre o Extremo Sul no 3o milénio a.n.e. Estudos oferecidos a Victor S. Gonçalves nos 30 anos da edição de Megalitismo e Metalurgia no Alto Algarve Oriental, uma aproximação integrada. Terra & Tempo. Estudos do Museu Municipal de Loulé 1. Loulé: Câmara Municipal de Loulé, pp. 399-438.

Sousa, A. C., Pereira, C., Miranda, M., Monge Soares, A., Odriozola, C. P. and Arruda, A. M. (2022). “Cabecinho da Capitôa (Mafra, Lisbon, Portugal). An Amber Necklace and Ceramic Vessels in Votive Contexts of the Western Iberian Late Bronze Age/Early Iron Age”. Madrider Mitteilungen, 63, pp. 42-75. DOI: https://doi.org/10.34780/99co-kc98.

Valera, A. C. (2017). “The ‘Exogenous’ at Perdigões. Approaching Interaction in the Late 4^th and 3^rd Millennium BC in Southwest Iberia”. In: Bartelheim, M., Bueno Ramírez, P. and Kunst, M. (Coords.). Key Resources and Sociocultural Developments in the Iberian Chalcolithic. Ressourcen Kulturen 6. Tübingen: Tübingen Library Publishing, pp. 201-224.

Vandkilde, H., Fischer Stephansen, C., Suchowska-Ducke, P., Ahlqvist, L., Skaaning Andersen, C., Felding, L.,… and Nørgaard, H. W. (2024). “Metal-for-Amber in the European Bronze Age”. Praehistorische Zeitschrift, 99 (1), pp. 280-338. DOI: https://doi.org/10.1515/pz-2024-2003.

Vijande Vila, E., Domínguez-Bella, S., Cantillo Duarte, J. J., Martínez López, J. and Barrena Tocino, A. (2015). “Social inequalities in the Neolithic of southern Europe: The grave goods of the Campo de Hockey necropolis (San Fernando, Cádiz, Spain)”. Comptes Rendus Palevol, 14 (2), pp. 147-161. DOI: https://doi.org/10.1016/j.crpv.2014.11.004.

Vilaça, R. (2006). “Artefactos de ferro em contextos do Bronze Final do território português: Novos contributos e reavaliação dos dados”. Complutum, 17, pp. 81-102.

Vilaça, R., Beck, C. W. and Stout, E. C. (2002). “Provenience analysis of prehistoric amber artifacts in Portugal”. Madrider Mittelungen, (43), pp. 61-78.

Vilaça, R. and Cardoso, J. L. (2017). “O Tejo português durante o Bronze Final”. In: Celestino Pérez, S. and Rodríguez González, E. (Eds.). Territorios comparados: los valles del Guadalquivir, el Guadiana y el Tajo en época tartésica. Anejos de Archivo Español de Arqueología, 80. Madrid: CSIC, pp. 237-281.

Villalobos García, R. (2016). Análisis de las transformaciones sociales en la Prehistoria Reciente de la Meseta Norte española (milenios VI-III cal a.C.). PhD Thesis. Universidad de Valladolid. Available at: https://uvadoc.uva.es/handle/10324/16693.

Villalobos García, R. and Odriozola, C. P. (2016). “Organizing the Production of Variscite Personal Ornaments in Later Prehistoric Iberia: The Mines of Aliste and the Production Sites of Quiruelas de Vidriales (Zamora, Spain)”. European Journal of Archaeology, 19 (4), pp. 631-651. DOI: https://doi.org/10.1080/14619571.2016.1147316.

_______________________________

1. Mineral archaeological classification System (Sánchez-Gómez et al., 2024Sánchez-Gómez, D., Odriozola Lloret, C. P., Sousa, A. C., Garrido-Cordero, J. Á., Romero-García, G., Martínez-Blanes, J. M.,… and Gonçalves, V. S. (2024). “A supervised multiclass framework for mineral classification of Iberian beads”. PLOS ONE, 19 (7), e0302563. DOI: https://doi.org/10.1371/journal.pone.0302563.).

2. Variscite origin recognition technology X-ray based (Sánchez-Gómez et al., 2025Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., García, R. V., Edo i Benaiges, M., Sousa, A. C.,… and Odriozola, C. P. (2025). “VORTEX (Variscite origin recognition technology X-ray based) Data. A European geoarchaeological green phosphate compositional dataset”. Data in Brief, 62, 111961. DOI: https://doi.org/10.1016/j.dib.2025.111961., 2026Sánchez-Gómez, D., Garrido-Cordero, J. Á., Martínez-Blanes, J. M., García, R. V., Sousa, A. C., Vega, M. D. Z.,… and Odriozola, C. P. (2026). “A Forest of Green Beads: A Machine-Learning Based Framework to Determine the Geological Provenance of Prehistoric Variscite Artifacts”. Journal of Archaeological Science, 185: 106428. DOI: https://doi.org/10.1016/j.jas.2025.106428.).

3. Também nos níveis superiores à camada eneolítica [refers to C1] foram encontrados muitos restos de cerâmicas de várias épocas assim como um peso de tear de idade do ferro e uma mola de prata de una fíbula de arco de tipo Hallstat (Mello et al., 1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249., p. 246). Translation to English: Also, in the levels above the Eneolithic layer [refers to C1] many remains of ceramics from various periods were found, as well as an Iron-Age loom weight and a silver spring from a Hallstat-type bow fibula.

4. Each sample was analyzed for approximately 60 seconds, with all chemical elements from magnesium (Mg) to uranium (U) measured and quantified. To ensure accuracy, 32-mm pellets of certified reference materials (BCR-032 #919 and GMB306-12) were analyzed at the beginning and end of each run.

5. Radiocarbon dating was conducted on only six of the twelve recovered individuals. The most recently dated individual is associated with Bell Beaker pottery and an amber bead.

6. SPD of 3620 ± 60 BP, GrA-20497, Human bone, intcal20 (Reimer et al., 2020Reimer, P. J., Austin, W. E., Bard, E., Bayliss, A., Blackwell, P. G., Ramsey, C. B.,… and Friedrich, M. (2020). “The IntCal20 Northern Hemisphere radiocarbon age calibration curve (0–55 cal kBP)”. Radiocarbon, 62 (4), pp. 725-757. DOI: https://doi.org/10.1017/rdc.2020.41.), 2 sigma, on rcarbon (Crema and Bevan, 2021Crema, E. and Bevan, A. (2021). “Inference from large sets of radiocarbon dates: software and methods”. Radiocarbon, 63, pp. 23-39. DOI: https://doi.org/10.1017/RDC.2020.95.).

7. In addition to these 15 copper-based items, Mello et al. (1961Mello, O. A. P. de, Fortuna, V., França, J. C., Ferreira, O. da V. and Roche, J. (1961). “O monumento pré-histórico da Bela Vista (Colares)”. Comunicações dos Serviços Geológicos de Portugal, 45, pp. 238-249., p. 243) document a Palmela-type arrowhead and a knife point, both of which are confidently dated to the 3^rd millennium BCE.