Mini journal logo  Home Issue Contents All Issues

The High-Status Late Medieval Skull Shaped Relic in Turku Cathedral, Finland – a study of its origin with oxygen and strontium isotope analyses

Maria Lahtinen

Cite this as: Lahtinen, M. 2022 The High-Status Late Medieval Skull Shaped Relic in Turku Cathedral, Finland - a study of its origin with oxygen and strontium isotope analyses, Internet Archaeology 59.


The Turku skull relic viewed from the side showing ornate red fabric with gold thread
The Turku skull relic viewed from the side (Photo: Aki Arponen/The Turku Cathedral Relic Project, Turku University/Archaeology)

The relics and associated reliquaries of Turku Cathedral are among the most significant early Christian artefacts in Finland preserved in situ. Despite their importance, they have not been the focus of scientific enquiry for a number of decades. This study has focused on one skull shaped relic, although the origin and name of its associated saint remains unknown. The relic is the only such example with high-status decoration in the Turku Cathedral collection and is covered with a red silk decorated with yellow yarn. The bones and fabric have been dated from the beginning of the modern era to the 13th century AD, and variance among the radiocarbon (14C) dates acquired from the bones shows the remains incorporate several individuals. In this study, oxygen and strontium isotope compositions were determined from fragmented bones and textiles. The results are the first isotope analysis performed on this collection housed in Turku Cathedral. Analysis indicates an origin from outside Finland, possibly elsewhere in northern Europe or an Alpine region. This helps take us a little closer to understanding the mystery associated with this sacred artefact.

  • Google Scholar
  • Keywords: relic, medieval, Sweden, Finland, isotope analysis, strontium, oxygen
  • Accepted: 3 June 2022. Published: 21 July 2022
  • Funding: This article was published with support of Danish-Finnish Cultural Foundation and the Finnish Academy (decision number 316431).
  • PDF download (main article text only)

Corresponding author: Maria LahtinenORCID logo
Department of Archaeology, U. Turku
Finnish Food Authority
U. Helsinki, Finnish Museum of Natural History

Full text

Figure 1: The Turku skull relic viewed from the side (Photo: Aki Arponen/The Turku Cathedral Relic Project, Turku University/Archaeology)

Figure 2: Scatter plot of calibrated 14C probability distributions (Bronk Ramsey 2017 using calibration curve Intcal 13) of bones and fabrics (dates published in Arponen 2015 and Arponen et al. 2018b)

Figure 3: Strontium isotope compositions (see also Table 1). Fabric samples lp6A-f and lp6B-f and lp13A-f and lp13B-f are from the same textile (one is from the warp, the other from the weft). From the bone lp 8 an additional control sample was taken. Fabric samples have lower mean strontium isotope composition than the bone samples

Figure 4: Scatter plot of oxygen isotope ratios (converted using Chenery et al. 2012 and Daux et al. 2008 no. 6 formula) and strontium isotope composition of bone samples analysed in this study. Two bone samples were collected from Ip8, Ip8A and Ip8B. Oxygen isotope composition of the fabric samples has not been studied

Figure 5: Map showing the interpolation of modern mean annual precipitation δ18Owsmow (data from, accessed 8.1.2018). The black shaded area indicates parts of Europe with comparable δ18Owsmow values to the range found in the study

Figure 6: Strontium isotope compositions determined from sites in Fennoscandia, Denmark and Estonia. A and B is this study; C = Denmark (Frei and Frei 2011); D = West Coast Sweden (Sjögren et al. 2009); E = Birka, Sweden (Gustin et al. 2017); F = Öland, Sweden (Fornander et al. 2014); G = Salberget, Sweden (Price et al. 2017); H & I = Iin Hamina, Finland – Salme (boat TAXIIIM), Estonia (Lahtinen et al. 2021); J = Rivers, Finland (Löfvendahl et al. 1990); K = Salme (boat TEXIC) and L = Salme (boat TAXIIIM), Estonia (Price et al. 2016); M = Estonia (Oras et al. 2016)

Table 1: Strontium isotope composition analysed in this study

Table 2: Results of the analysis of fabric pre-treatment solutions. The residue is the isotope composition of the fabric that remained after the pre-treatments.

Table 3: Oxygen and carbon isotope composition from bone carbonate. VSMOW CAC et al. has been calculated using Chenery et al. (2012) and Daux et al. (2008) conversion results using formulas 4 and 6

Arponen, A. 2015 'The medieval skull relic of Turku Cathedral – preliminary results of analyses', Verkkojulkaisu Mirator, Helsinki. Glossary, 104–16.

Arponen, A., Vanden Berghe, I. and Kinnunen, J. 2018a 'Red fabrics in the relic assemblage of Turku Cathedral' in M. Van Strydonck, J. Reyniers and F. Van Cleven (eds) 'Relics @ the Lab. An analytical approach to the study of relics', Interdisciplinary Studies in Ancient Culture and Religion 20, Leuven: Peeters Publishers. 3–19.

Arponen, A., Maijanen, H. and Immonen, V. 2018b 'From bones to sacred artefact: the late medieval skull relic of Turku Cathedral, Finland', Temenos 54(2), 149–83.

Bentley, A.R. 2006 'Strontium Isotopes from the earth to the archaeological skeleton: a review', Journal of Archaeological Method and Theory 13(3), 135–87.

Bowen, G.J. and Wilkinson, B. 2002 'Spatial distribution of δ18O in meteoric precipitation', Geology 30(3), 315–18.<0315:SDOOIM>2.0.CO;2

Branting, A. and Lindblom, A. 1928 Medeltida vävnader och broderier i Sverige, Uppsala.

Bronk Ramsey, C. 2017 'Methods for Summarizing Radiocarbon Datasets', Radiocarbon 59(2), 1809–1833.

Burger, A. and Lichtscheidl, I. 2019 'Strontium in the environment: review about reactions of plants towards stable and radioactive strontium isotopes', Science of the Total Environment 653, 1458–1512.

Charlier, B.L.A., Ginibre, C., Morgan, D., Nowell, G.M., Pearson, D.G., Davidson, J.P. and Ottley, C.J. 2006 'Methods for the microsampling and high-precision analysis of strontium and rubidium isotopes at single crystal scale for petrological and geochronological applications', Chemical Geology 232(3), 114-33.

Chenery, C.A., Pashley, V., Lamb, A.L., Sloane, H.J. and Evans, J. 2012 'The oxygen isotope relationship between the phosphate and structural carbonate fractions of human bioapatite', Rapid Communications in Mass Spectrometry 26(3), 309–19.

Clarke, B. 2008 'Normal bone anatomy and physiology', Clinical Journal of the American Society of Nephrology 3, S131–S139.

Darling, W.G., Bath, A H. and Talbot, J.C. 2003 'Check this. The O & H stable isotopic composition of fresh waters in the British Isles. 2. Surface waters and groundwater', Hydrology and Earth System Sciences 7(2), 183–95.

Daux, V., Lécuyer, C., Héran, M.-A., Amiot, R., Simon, L., Fourel, F., Martineau, F., Lynnerup, N., Reychler, H. and Escarguel, G. 2008 'Oxygen isotope fractionation between human phosphate and water revisited', Journal of Human Evolution 55(6), 1138–47.]10.1016/j.jhevol.2008.06.006

Evans, J.A., Montgomery, J., Wildman, G. and Boulton, N. 2010 'Spatial variations in biosphere 87Sr/86Sr in Britain', Journal of the Geological Society 167. Dataset.

Evans, J., Chenery, C. and Montgomery, J. 2012 'A summary of strontium and oxygen isotope variation in archaeological human tooth enamel excavated from Britain', Journal of Analytical Atomic Spectrometry 27(5), 754-764.

Fornander, E., Lidén, K., Eriksson, G. and Andersson, P. 2014 'Identifying mobility in populations with mixed marine/terrestrial diets: strontium isotope analysis of skeletal material from a passage grave in Resmo, Öland, Sweden' in P. Suchowska-Ducke and H. Vandkilde (eds) Forging Identities: Mobility of Culture in Bronze Age Europe. Report from a Marie Curie Project 2009-2012 with Concluding Conference at Aarhus University, Moesgaard 2012: Volume 2, Brit. Archaeol. Rep. Int. Series S2772, Oxford: Archaeopress. 1–13.

Frei, K.M. 2012 'Exploring the potential of the strontium isotope tracing system in Denmark', Danish Journal of Archaeology 1, 113–22.

Frei, K.M. 2013 'Exploring the potential of the strontium isotope tracing system in Denmark', Danish Journal of Archaeology 1(2), 113–22.

Frei, K.M. 2014 'Provenance of archaeological wool textiles: new case studies', Open Journal of Archaeometry 2(1).

Frei, K.M. and Frei, R. 2011 'The geographic distribution of strontium isotopes in Danish surface waters – a base for provenance studies in archaeology, hydrology and agriculture', Applied Geochemistry 26(3), 326–40.

Frei, K.M., Berghe, I.V., Frei, R., Mannering, U. and Lyngstrøm, H. 2010 'Removal of natural organic dyes from wool–implications for ancient textile provenance studies', Journal of Archaeological Science 37, 2136–45.

Gustin, I., Price, D.T., Arcini, C., Drenzel, L. and Kalmring, S. 2017 'Isotopes and human burials at Viking Age Birka and the Mälaren Region, East Central Sweden', Journal of Anthropological Archaeology 49, 19-38.

Halicz, L., Segal, I., Fruchter, N., Stein, M. and Lazar, B. 2008 'Strontium stable isotopes fractionate in the soil environments?', Earth and Planetary Science Letters 272(1–2), 406–11.

Hartmann-Virnich, A. 2011 'Réflexions sur l'abbatiale romane de Saint-Ruf d'Avignon' in Provence historique, Tome LXI, Fascicule 243–244, Janvier-juin 2011, 323–38, Histoire et archéologie de la Provence antique et médiévale. 323-338.

Heikkilä, T.M. 2005 Pyhän Henrikin legenda, Suomalaisen Kirjallisuuden Seuran toimituksia 1039, Suomalaisen Kirjallisuuden Seura, Helsinki.

Heikkilä, T.M. 2016 'Tracing the Heavenly pater patriae of Medieval Finland: The Relics of St Henry of Uppsala' in M. Räsänen, G. Hartmann and E.J. Richards (eds) Relics, Identity, and Memory in Medieval Europe, Europa Sacra, 21, Brepols. 224-254.

Heijmans, M. 2013 'Arelate (Arles)' in R.S. Bagnall, K.Brodersen, C.B. Champion, A. Erskine and S.R.Huebner (eds) The Encyclopedia of Ancient History, Oxford: Blackwell Publishing Ltd. 668–69.

Hiekkanen, M. 2002 'Die Gründung der Stadt Turku' in E. Mugurēvičs and I. Ose (eds) Civitas et Castrum ad Maris Baltici, Riga: Latvijas vēstures institūts. 157–77.

Hiekkanen, M. 2010 'Burial practices in Finland from bronze age to the early middle ages' in B. Nilsson (ed) Från hedniskt till kristet: förändringar i begravningsbruk och gravskick i Skandinavien c:a 800-1200. 271-379.

Hoogewerff, J.A., Reimann, C., Ueckermann, H. et al. 2019 'Bioavailable 87Sr/86Sr in European soils: a baseline for provenancing studies', Science of the Total Environment 672, 1033–44.

Kaislaniemi, L. 2011 'Estimating the distribution of strontium isotope ratios (87Sr/86Sr) in the Precambrian of Finland', Bulletin of the Geological Society of Finland 83(2), 95-113.

Klockars, B. 1960 Biskop Hemming av Åbo', Skrifter utgivna av Svenska Litteratursällskapet i Finland nr 379, Helsingfors: Svenska Litteratursällskapet i Finland.

Kortelainen, N. 2007 Isotopic Fingerprints In Surficial Waters: Stable Isotope Methods Applied In Hydrogeological Studies, PhD thesis, University of Helsinki.

Lahti, S. 2003 'Turun tuomiokirkon reliikit ja relikvaariot', Mirator 18, 1-18.

Lahti, S. 2019 Silver Arms and Silk Heads, Turku: Åbo Akademi University Press.

Lahtinen, M., Arppe, L. and Nowell, G. 2021 'Source of strontium in archaeological mobility studies—marine diet contribution to the isotopic composition', Archaeological and Anthropological Sciences 13(1), 1-10.

Lightfoot, E. and O'Connell, T.C. 2016 'On the use of biomineral oxygen isotope data to identify human migrants in the archaeological record: intra-sample variation, statistical methods and geographical considerations', PLOS ONE 11(4), e0153850.

Longinelli, A. 1984 'Oxygen isotopes in mammal bone phosphate: a new tool for paleohydrological and paleoclimatological research?', Geochimica et Cosmochimica Acta 48, 385–90.

Löfvendahl, R., Åberg, G. and Hamilton, P.J. 1990 'Strontium in rivers of the Baltic Basin', Aquatic Sciences 52(4), 1015–1621.

Malin, A. 1925 Der Heiligenkalender Finnlands. Seine Zusammensetzung und Entwicklung, Helsinki: Suomen Kirkkohistoriallinen Seura.

Montgomery, J. 2010 'Passports from the past: investigating human dispersals using strontium isotope analysis of tooth enamel', Annals of Human Biology 37, 325–46.

Nelson, B.K., Deniro, M.J., Schoeninger, M.J., De Paolo, D.J. and Hare, P.E. 1986 'Effects of diagenesis on strontium, carbon, nitrogen and oxygen concentration and isotopic composition of bone', Geochimica et Cosmochimica Acta 50, 1941–49.

Newman, C. and Michel, J. 2013 'La nécropole grecque du Lazaret d'Arenc', Archéothéma 29, 40-41.

Nordman, C.A. 1954 'En relik av Erik den helige I Åbo domkyrka' in Bengt Thordeman (ed) Erik den Helige, historia – kult – reliker. Stockholm: Nordisk rotogravyr. 303–20.

Oras, E., Lang, V., Rannamäe, E., Varul, L., Konsa, M., Simovart-Limbo, J., Vudru, G., Laneman, M., Malve, M. and Price, T.D. 2016 'Tracing prehistoric migration: isotope analysis of bronze and pre-roman iron age coastal burials in Estonia', Estonian Journal of Archaeology 20, 3–32.

Price, T.D., Naum, M., Bennike, P., Lynnerup, N., Frei, K.M., Wagnkilde, H., Pind, T. and Nielsen, F.O. 2013 'Isotopic investigation of human provenience at the eleventh century cemetery of Ndr. Grødbygård, Bornholm, Denmark', Danish Journal of Archaeology 1(2), 93–112.

Price, T.D., Peets, J., Allmäe, R., Maldre, L. and Oras, E. 2016 'Isotopic provenancing of the Salme ship burials in Pre-Viking Age Estonia', Antiquity 90(352), 1022–37.

Price, T.D., Frei, R., Bäckström, Y., Frei, K.M. and Ingvarsson-Sundstrom, A. 2017 'Origins of inhabitants from the 16th century Sala (Sweden) silver mine cemetery – a lead isotope perspective', Journal of Archaeological Science 80, 1–13.

Rinne, J. 1932 Pyhä Henrik, piispa ja marttyyri, Suomen kirkkohistoriallisen seuran toimituksia 33, Helsinki: Otava.

Rinne, J. 1948 Turun tuomiokirkko keskiaikana. II Alttarit ja kirkolliset toimitukset, Turku: Turun tuomiokirkon isännistö.

Schürch, M., Kozel, R., Schotterer, U. and Tripet, J.P. 2003 'Observation of isotopes in the water cycle - the Swiss National Network (NISOT)', Environmental Geology 45(1), 1–11.

Sjögren, K.-G., Price, T.D. and Ahlström, T. 2009 'Megaliths and mobility in south-western Sweden. Investigating relationships between a local society and its neighbours using strontium isotopes', Journal of Anthropological Archaeology 28(1), 85–101.

Taavitsainen, J-P. 2011 'Interdisciplinary perspectives on the medieval relics and reliquaries of Turku cathedral, Finland', Material Religion 7(3), 44-450.

Taavitsainen, J-P, Arponen A., Tamm, J., Putkonen, M., Hornytzkyj, S., Lahtinen-Kaislaniemi, M. and Possnert, G. 2018 'Relics from the Pirita Bridgettine Convent near Tallinn - Viis reliikviat Pirita birgitiinide kloostrist' in E. Russow and V. Lang (eds) Pühakud, piiskopid, linnad ja linnused: Ajarännakuid kesk- ja varauusaega, Muinasaja Teadus, no. 27, Tallinna Ülikool. 217-42.

Thirlwall, M.F. 1991 'Long-term reproducibility of multicollector Sr and Nd isotope ratio analysis', Chemical Geology: Isotope Geoscience section 94(2), 85-104.

Ukkonen, P. 1993 'The post-glacial history of the Finnish mammalian fauna', Annales Zoologici Fennici 30(4), 249–64.

Vajanto, K. 2013 'Fibre analysis of Late Iron Age and Early Medieval and Modern Finnish wools', Fennoscandia archaeologica XXX, 81-94.

Voerkelius, S., Lorenz, G.D., Rummel, S., Quétel, C.R., Heiss, G., Baxter, M., Brach-Papa, C., Deters-Itzelsberger, P., Hoelzl, S., Hoogewerff, J., Ponzevera, E., Van Bocxstaele, M. and Ueckermann, H. 2010 'Strontium isotopic signatures of natural mineral waters, the reference to a simple geological map and its potential for authentication of food', Food Chemistry 118(4), 933–40.

Internet Archaeology is an open access journal based in the Department of Archaeology, University of York. Except where otherwise noted, content from this work may be used under the terms of the Creative Commons Attribution 3.0 (CC BY) Unported licence, which permits unrestricted use, distribution, and reproduction in any medium, provided that attribution to the author(s), the title of the work, the Internet Archaeology journal and the relevant URL/DOI are given.

Terms and Conditions | Legal Statements | Privacy Policy | Cookies Policy | Citing Internet Archaeology

Internet Archaeology content is preserved for the long term with the Archaeology Data Service. Help sustain and support open access publication by donating to our Open Access Archaeology Fund.