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Archaeological excavations in the Podravina region led to discovery of sites with traces of bloomery iron production during Late Antiquity and the Early Middle Ages. Mineralogical analysis of the slags recognized fayalite as the main mineral phase, while geochemical analysis confirmed high Fe contents, typical for bloomery iron smelting. Based on the previously established occurrences of bog iron ores in the study area, provenance studies were carried out using trace and rare earth elements to create a geochemical signature. Similar shapes and patterns of bog iron ores and iron slag signatures imply a genetic connection between the ore and the slag, as well as variation related to the temporal and spatial context of both slags and ores.

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The Vijenac limestone quarry, near Tuzla in Bosnia and Herzegovina, is composed of carbonate rocks locally embedding tectonically disturbed siltite and sandstone with Fe-Mn concretions. The quarry itself represents a part of Dinaric overstep sequences (the Pogari Formation) unconformably overlying ophiolite mélange and ophiolite trust-scheets. Petrographic, chemical and mineralogical analyses had shown that the concretions may be divided into two types: (i) Mn-rich concretions with 17 wt.% of Mn and compact texture and (ii) Mn-poor with 8 wt.% of Mn and porous texture. The amount of Ca, Fe and Mg in both concretion types are similar. Nickel and Cr positively correlate with Fe and Mn, respectively. According to petrographic and mineralogical analyses, concretions are composed of calcite, dolomite, hematite, todorokite and takanelite. Petrographic study con rmed the development of concretions within three stages including two generations of calcite. Studied concretions are formed within consolidated sandstones inheriting their sedimentary textures-therefore a late diagenetic process is assumed.