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Titel |
Geochemical and mineralogical composition of bog iron ore as a resource for prehistoric iron production – A case study of the Widawa catchment area in Eastern Silesia, Poland |
VerfasserIn |
Michael Thelemann, Wiebke Bebermeier, Philipp Hoelzmann |
Konferenz |
EGU General Assembly 2016
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 18 (2016) |
Datensatznummer |
250128256
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Publikation (Nr.) |
EGU/EGU2016-8229.pdf |
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Zusammenfassung |
Spreading from the Near East in the declining Bronze Age from the 2nd millennium BCE
onwards, the technique of iron smelting reached Eastern Silesia, Poland, in approximately the
2nd century BCE (pre-Roman Iron Age). At this time the region of the Widawa catchment
area was inhabited by the Przeworsk culture. While the older moraine landscape of the study
area lacks ores from geological rock formations, bog iron ores were relatively widespread
and, due to their comparatively easy accessibility, were commonly exploited for early iron
production. In this poster the mineralogical and elemental composition of local bog
iron ore deposits and iron slag finds, as a by-product of the smelting process, are
investigated.
The crystalline mineralogical composition of local bog iron ores is dominated by quartz
(SiO2) and goethite (α FeO(OH)), in contrast to slag samples in which fayalite (Fe2SiO4),
wüstite (FeO) and quartz, with traces of goethite, represent the main minerals. Ores and slags
are both characterized by notable hematite (Fe2O3), magnetite (Fe3O4) and maghemite
(γ-Fe2O3) contents. Analyzed bog iron ore samples show iron contents of up to
64.9 mass% Fe2O3 (45.4 mass% Fe), whereas the iron contents of bloomery slags
vary between 48.7 and 72.0 mass% FeO (37.9 and 56.0 mass% Fe). A principal
component analysis of the element contents, which were quantified by portable
energy-dispersive X-ray fluorescence spectrometry (p-ED-XRF), indicates local
variations in the elemental composition. Our results show that bog iron ores are
relatively widely distributed with spatially varying iron contents along the Widawa
floodplain but present-day formation conditions (e.g. different ground-water levels) are
negatively affected by modern land-use practices, such as agriculture and melioration
measures. |
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