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A lost iron realm?Iron production in southern Hälsingland during the late iron age This bachelor thesis explores the prehistoric iron production in the Swedish province of Hälsingland, with a special focus on the parishes surrounding the Marmen and Bergviken lakes. A vast amount of remains from bloomery iron production was discovered during the 1980’s in the area surrounding the lakes, consisting of iron making sites and charcoal pits. This thesis focuses on the spatial distribution of those remains, which are studied and analysed mainly through GIS. Their spatial relation to natural-geographical phenomenon and indicators of settlement is analysed and discussed, with comparisons to other Swedish provinces. In addition, 14C-datings are calibrated and discussed on a critical basis. The occurrence of spade-shaped currency bars in Hälsingland is discussed based on their physical appearance and context of finding. Finally the author suggests how to work with the known material in order to gain new scientific knowledge.

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The author has categorized and analysed slag deposits in different contexts. The categories are as such: slag on arable land, slag and mounds, slag at graves, slag as grave, slag at settlements and slag at the outskirts. Ironmaking sites and slag heaps appear in contexts that suggest they may have been perceived as symbolically significant for the farm's inhabitants and was included in common ritual practices. There is reason to believe that ironmaking sites and slag heaps have interacted with people and given rise to ideological thoughts, this includes the Odal mentality. Also, the construction of burial fields near ironmaking sites and vice versa, could demonstrate a connection with the past. Iconographic motifs and Norse texts reflect symbolic aspects of iron handling, especially craft and blacksmithing are portrayed as activities associated with ideologically important stories. Ironmaking sites are also found to be connected to symbolically important places such as Torsåker, Vi, etc.

Outlying forest and mountain areas in the inland of middle and north Scandinavia have for a long time been seen as marginal areas of little importance to the main Scandinavian historical narrative. However, in recent time, the importance of the outland has increasingly been in the focus of archaeological research. It has been suggested by several scholars that the emergence of centralized power structures in various parts of Scandinavia during the mid Iron Age can be explained by an extensive trade of resources like antler, bone, and iron. However, much is still unknown about the broader context of these activities and the people that performed them. The aim of this study is to analyse the character of these activities and exchange networks in a study area consisting of areas on both sides of the present Swedish-Norwegian border. This is done by analysing the pattern of archaeological remains in the outland and how they relate to landscape characteristics like topography, water courses and sediment types. The main archaeological remains studied are graves, pitfalls for moose and reindeer hunting and iron working sites. The results show the use of graves as territorial markers in the landscape and the existence of central places in the outland, possibly used for trade and social activities. The study also suggests that the relations between people from the hunter-gatherer and the agrarian communities changed during the late Iron Age, which is indicated by a dislocation of graves further up in the valleys to the north.

Denna uppsats behandlar frågan kring en eventuell förekomst av centralplatser eller centralplatsområden under järnåldern (ca 500 f.Kr. - 1050 e.Kr.) i det som idag är Småland. Utgångspunkten är tidigare forskning inom området järnålderns centralplatser, främst i Sydskandinavien, samt några av de centralplatsindikerande förklaringsmodeller, främst då Charlotte Fabech och Jytte Ringtved (1995) som bedöms applicerbara i föreliggande studie om Smålands järnålder. Sammantaget bedöms det sammantagna källmaterialet från järnåldern, med tyngdpunkt på ett flertal centralplatsindikerande fyndkategorier, så som prakt- ädelmetall- och vapenfynd, samt förekomst av olika typer av hantverksfynd, produktionsverksamhet och metallbearbetning, främst järnhantering. Därutöver läggs särskild vid de under järnåldern föreliggande resursmässiga och kommunikativa förutsättningarna. Vidare undersöks ortnamnsaspekten som en möjlig centralplatsindikerande faktor. Också huruvida man genom att utgå från den medeltida häradsindelningen kan underlätta en centralområdesidentifiering, utforskas inom ramen för detta uppsatsarbete. / This study deals with the question whether there are any archeaological traces or evidence of central places or central areas in the Swedish province of Småland dating back to the Iron Age (circa 500 B.C - 1050 AD). The basis of this study is primarily the arceological data consisting of different arcehological remains such as traces of settlement and habitation, graves and grave finds and iron making. Additionaly the presence of central place- indicating place names are considered.

This master's thesis covers an investigation of the reduction behavior of different iron oxides when electrolytically reduced with molten salt electrolysis (MSE). The tested iron oxides were wüstite (FeO), hematite (Fe2O3), magnetite (Fe3O4) and magnetite ore concentrate from the Tapuli deposit in Pajala, Norrbotten, Sweden. The properties of the Tapuli magnetite ore and magnetite ore concentrate were analysed from a mineralogical perspective to evaluate how the raw ore material influences the concentrate and its reduction by the MSE technology. The electrolytic experiments were performed in an Inconel 625 cell body within a pit-furnace. The different iron oxides were tested separately. The reduction samples were constructed of one or three iron oxide briquettes of 20 g each within a molybdenum mesh attached on a molybdenum tray with molybdenum wires. The molten electrolyte was kept at 500°C with an applied voltage of 1.7 or 2.1 V. The used electrolyte was sodium hydroxide (NaOH). The mineralogical examination shows that the Tapuli ore varies in composition between different locations of the deposit with respect to magnetite grain size and skarn composition and grain size. Point analyses with Laser Ablation Single Collector Inductively Coupled Plasma Mass Spectrometry (LA-SC-ICP-MS) on magnetite grains in thin sections from five drill cores fromdifferent parts of the deposit show that the element composition in the magnetite grains vary between the samples. Core-to-rim analyses for Fe, Mg, Mn and Al reveal relatively homogenous grades throughout the grains, with a few exceptions. Phase analysis with XRD shows that reduction has occurred in all tested iron oxides. Without prevention, the reduction products from trials on Fe2O3, Fe3O4 and magnetite ore concentrate show distinct XRD peaks of the by-product NaFeO2. According to XRD, the addition of Na2O seems to have reduced the NaFeO2 formation. Interestingly, no NaFeO2 was formed in the FeO trials. This might be explained by the absence of Fe3+ in FeO. The variation of the current-time curves of the trials is interpreted to depend on the voltage applied, the number of briquettes, briquette decomposition and Na2O addition. Electrolysis in molten NaOH can be used to reduce iron oxides. Despite this, NaOH might not be a suitable electrolyte for this process due to its interaction with Fe2O3 and Fe3O4 resulting information of NaFeO2. Na2O can be used as an additive to prevent formation of NaFeO2 but sharply decreases the current response, thus having an apparent negative effect on the process efficiency. Another preventive measure that can be tested is to calibrate the process voltage to decompose the NaFeO2 but not NaOH. Due to the shown interaction tendency of NaOH, other electrolytes should however be considered for this process. Regarding the Tapuli ore concentrate, more tests are needed to draw conclusions about how the trace elements effects its electrolytic behavior. / Denna masteruppsats avhandlar en undersökning av reduktionsbeteendet hos olika järnoxider vid elektrolytisk reduktion i saltsmälta (molten salt electrolysis (MSE)). Järnoxiderna som har testats är wüstit (FeO), hematit (Fe2O3), magnetit (Fe3O4) och magnetitmalmkoncentrat från malmfyndigheten Tapuli i Pajala, Norrbotten, Sverige. Malmkoncentratets egenskaper har analyserats ur mineralogisk synvinkel för att utvärdera hur den råa malmens mineralogi påverkar koncentratet och dess reduktionsbeteende vid elektrolys i saltsmälta. Elektrolysexperimenten utfördes i cellkropp av Inconel 625 placerad i en gropugn. De olika järnoxiderna testades separat. Reduktionsproverna utgjordes av en eller tre järnoxidbriketter på 20 g inuti ett molybdennät, fastvirade på en molybdenbricka med molybdentråd. Den smälta elektrolyten hölls vid en temperatur av 500°C med en applicerad spänning av 1.7 eller 2.1 V. Elektrolyten som användes var natriumhydroxid (NaOH). Den mineralogiska undersökningen visar att tapulimalmens sammansättning varierar mellan olika delar av fyndigheten med avseende på magnetitens kornstorlek och skarnets sammansättning och kornstorlek. Punktanalyser med Laser Ablation Single Collector Inductively Coupled Plasma Mass Spectrometry (LA-SC-ICP-MS) på magnetitkorn i tunnslip från fem olika borrkärnor visar att elementkoncentrationerna i magnetitkornen varierar mellan proverna. Core-to-rim-analyser på magnetitkornen visar att halterna av Fe, Mg, Mn och Al är tämligen homogena genom hela magnetitkornet med undantag av några få avvikande punkter. Fasanalys med XRD indikerar att reduktion har skett i alla försök. Utan prevention visar reduktionsprodukterna från försöken på Fe2O3, Fe3O4 och magnetitmalmkoncentrat klara indikationer av biprodukten NaFeO2. Enligt XRD verkar tillsats av Na2O ha minskat bildningen av Na2O för Fe2O3, Fe3O4 och Tapuli magnetitmalmkoncentrat. Intressant är att ingen NaFeO2 bildades i försöken med FeO. Förklaringen till detta skulle kunna vara avsaknaden av Fe3+ i FeO. De varierande ström-tidkurvorna från försöken tolkas bero på den applicerade spänningen, antalet briketter, brikettsönderdelning och tillsats av Na2O. Elektrolys i smält NaOH kan användas för att reducera järnoxider. Trots detta kanske NaOH inte är lämplig som elektrolyt i denna process, detta på grund av dess påvisade interaktion med Fe2O3 och Fe3O4 som resulterar i bildning av NaFeO2. Na2O kan tillsättas för att förhindra bildning av NaFeO2 men har en kraftigt negativ effekt på strömstyrkan i processen vilket minskar processens effektivitet. En annan preventiv åtgärd som kan testas är att kalibrera processens spänning så att NaFeO2 sönderdelas men inte NaOH. På grund av den konstaterade interaktionstendensen hos NaOH bör andra elektrolyter tas i beaktande för denna process. Angående magnetitmalmskoncentratet från Tapuli behövs fler tester för att dra slutsatser kring hur spårelementen påverkar dess uppförande vid smältelektrolys.