Bog Iron Research Articles

Questioning Fe isotopes as a provenance tool: Insights from bog iron ores and alternative applications in archeometry

Provenancing metal artifacts with scientific methods is an established tool in archeometry to identify the metal deposits, which were exploited for the production of ancient metal objects. It is thus an important method to reconstruct ancient exchange networks and the socio-economic organization of past societies. Previously introduced isotope-based approaches (Pb, Sr, Os) and chemical analyses of slag inclusions have severe limitations concerning their application or the amount of sample required. Fe isotopes were previously suggested in a quite early stage of investigation as a potential provenance tracer and it was postulated that they would not fractionate during the smelting procedure. However, previously published analytical data from iron ores indicate a wide overlap between deposits. Further, the earlier studies on Fe isotopes did not included bog iron ores, despite their high importance in ancient metallurgy. As geochemical reactions during ore formation are complex and fractionation cannot be generally excluded, the applicability of Fe isotopes as an alternative provenance tracer still asks for further investigation.This purely methodological study focuses on specimens from two sites of the formerly mined bog iron ore deposit Eyller Bruch (Germany), which are analyzed together with products of a smelting experiment based on these ores. The Fe isotopic composition of the bog iron ore from the investigated region suggests an intra-deposit zonation caused by environmental parameters and its overall variation is comparable with that of other deposits. The bog iron ore isotope signature largely overlaps with the isotope range of mineralizations in other regions. As a consequence of this and although the absence of Fe isotope fractionation during the smelting procedure is confirmed, the study demonstrates the lack of discriminatory power of Fe isotopes for provenance studies. Potential applications for archeometry can rather be found in the environmental parameters, especially organic matter, which seems to have a strong influence on Fe isotope compositions of bog iron ores. Zonations within deposits might be identified and could help to reconstruct the exploitation history of the deposit or to reconstruct past bog landscapes.

Genomic and Biotechnological Characterization of the Heavy-Metal Resistant, Arsenic-Oxidizing Bacterium Ensifer sp. M14.

Ensifer (Sinorhizobium) sp. M14 is an efficient arsenic-oxidizing bacterium (AOB) that displays high resistance to numerous metals and various stressors. Here, we report the draft genome sequence and genome-guided characterization of Ensifer sp. M14, and we describe a pilot-scale installation applying the M14 strain for remediation of arsenic-contaminated waters. The M14 genome contains 6874 protein coding sequences, including hundreds not found in related strains. Nearly all unique genes that are associated with metal resistance and arsenic oxidation are localized within the pSinA and pSinB megaplasmids. Comparative genomics revealed that multiple copies of high-affinity phosphate transport systems are common in AOBs, possibly as an As-resistance mechanism. Genome and antibiotic sensitivity analyses further suggested that the use of Ensifer sp. M14 in biotechnology does not pose serious biosafety risks. Therefore, a novel two-stage installation for remediation of arsenic-contaminated waters was developed. It consists of a microbiological module, where M14 oxidizes As(III) to As(V) ion, followed by an adsorption module for As(V) removal using granulated bog iron ores. During a 40-day pilot-scale test in an abandoned gold mine in Zloty Stok (Poland), water leaving the microbiological module generally contained trace amounts of As(III), and dramatic decreases in total arsenic concentrations were observed after passage through the adsorption module. These results demonstrate the usefulness of Ensifer sp. M14 in arsenic removal performed in environmental settings.

Granulated Bog Iron Ores as Sorbents in Passive (Bio)Remediation Systems for Arsenic Removal.

The main element of PbRS (passive (bio)remediation systems) are sorbents, which act as natural filters retaining heavy metals and carriers of microorganisms involved in water treatment. Thus, the effectiveness of PbRS is determined by the quality of the (ad)sorbents, which should be stable under various environmental conditions, have a wide range of applications and be non-toxic to (micro)organisms used in these systems. Our previous studies showed that bog iron ores (BIOs) meet these requirements. However, further investigation of the physical and chemical parameters of BIOs under environmental conditions is required before their large-scale application in PbRS. The aim of this study was (i) to investigate the ability of granulated BIOs (gBIOs) to remove arsenic from various types of contaminated waters, and (ii) to estimate the application potential of gBIOs in technologies dedicated to water treatment. These studies were conducted on synthetic solutions of arsenic and environmental samples of arsenic contaminated water using a set of adsorption columns filled with gBIOs. The experiments performed in a static system revealed that gBIOs are appropriate arsenic and zinc adsorbent. Dynamic adsorption studies confirmed these results and showed, that the actual sorption efficiency of gBIOs depends on the adsorbate concentration and is directly proportional to them. Desorption analysis showed that As-loaded gBIOs are characterized by high chemical stability and they may be reused for the (ad)sorption of other elements, i.e., zinc. It was also shown that gBIOs may be used for remediation of both highly oxygenated waters and groundwater or settling ponds, where the oxygen level is low, as both forms of inorganic arsenic (arsenate and arsenite) were effectively removed. Arsenic concentration after treatment was <100 μg/L, which is below the limit for industrial water.

XRD, SEM/EDX and micro-Raman spectroscopy for mineralogical and chemical characterization of iron slags from the Roman archaeological site of Forua (Biscay, North Spain)

The Roman village of Forua (North Spain) was an important iron production and distribution centre during the 1st-4th centuries AD. Different metallurgical materials at the archaeological site were identified as forged slag, bog ore mineral and refractory materials used in the walls and on the floor of furnaces. The samples were studied by macroanalysis and microanalysis techniques. The mineralogical characterization was carried out via optical microscopy and X-ray powder diffraction, and the textural characteristics and the composition of individual phases were determined using scanning electron microscopy coupled with electron-dispersive spectroscopy, and by Raman microspectroscopy. Mineral associations not only reflect furnace cooling rates and temperatures but also indicate quartz was the main flux used. The microanalysis results reflect the elements that constituted the slags and other materials from the forge and the worked metallic materials. The results showed the slags originated from iron smithing, which also was confirmed by the presence of iron particles. The ore materials consisted of goethite.

Early Piast dynasty (10–11th century) stone architecture in western Poland in a geological context

There is no consistency in reporting the stone material used to construct the first structures in the early Piast dominion (10–11th century) in Poland. The role and importance of the type of the stone building material used at that time has been underappreciated if not completely ignored. It has been stated that glacial erratics comprise the fundamental rock material used in the early Middle Ages for building, representing up to 98% of construction material. The remaining rocks used in building construction included local calcareous sinter, bog iron ores, Jurassic limestone from the Piechciny-Barcin region and gypsum from a salt dome in the village of Wapno in western Poland, while Miocene sandstone excavated at the inception of the Polish state in the Brzeźno Quarry near Konin has received significant attention. There appear to have been distinct phases of use of the various types of rock material. There was likely a link between the development of tillage and the development of monumental stone architecture from the Middle Ages. Deforestation resulting from the development of agriculture helped expose the glacial erratics used in the stone architecture of the first Piast rulers

The influence of thermal treatment on bioweathering and arsenic sorption capacity of a natural iron (oxyhydr)oxide-based adsorbent

Adsorption plays a significant role in remediation of waters contaminated with arsenic, but the efficiency of the process varies depending on the sorbent properties. Bog iron ores (BIOs), characterized by high sorption capacity and widespread availability, seem to be an optimal sorbent of arsenic. However, the use of BIOs for arsenic removal from waters may be limited by the high amount of organic matter, which may stimulate microbial activity, and thus decomposition of the sorbent. The aim of this study was to determine the effect of organic matter removal by thermal transformation (roasting) on the bioavailability of BIOs and their arsenic sorption capacity. For this purpose, the influence of bacterial growth and activity on untreated and treated BIOs, unloaded and loaded with arsenic, was studied. Moreover, the chemical and physical properties (including FTIR and desorption of arsenic) of BIOs were investigated as well. The results show that the removal of organic matter increases the stability of BIOs, and thus reduces the bioavailability of the immobilized arsenic.

Draft Genome Sequence of Ideonella sp. Strain A 288, Isolated from an Iron-Precipitating Biofilm.

ABSTRACTHere, we report the draft genome sequence of the betaproteobacterium Ideonella sp. strain A_228. This isolate, obtained from a bog iron ore-containing floodplain area in Germany, provides valuable information about the genetic diversity of neutrophilic iron-depositing bacteria. The Illumina NextSeq technique was used to sequence the draft genome sequence of the strain.

Iron-containing phases in metallurgical and coke dusts as well as in bog iron ore

Abstract Several samples of dusts from steel and coke plants (collected mostly with electro filters) were subjected to the investigation of content of mineral phases in their particles. Additionally, sample of bog iron ore and metallurgical slurry was studied. Next, the magnetic susceptibility of all the samples was determined, and investigations of iron-containing phases were performed using transmission Mössbauer spectrometry. The values of mass-specific magnetic susceptibility χ varied in a wide range: from 59 to above 7000 × 10−8 m-3·kg−1. The low values are determined for bog iron ore, metallurgical slurry, and coke dusts. The extremely high χ was obtained for metallurgical dusts. The Mössbauer spectra and X-ray diffraction patterns point to the presence of the following phases containing iron: hematite and oxidized magnetite (in coke and metallurgical dusts as well as metallurgical slurry), traces of magnetite fine grains fraction (in metallurgical dusts), amorphous glassy silicates with paramagnetic Fe3+ and Fe2+ ions, traces of pyrrhotite (in coke dusts), α-Fe and nonstoichiometric wüstite (in metallurgical slurry), as well as ferrihydrite nanoparticles (in bog iron ore). For individual samples of metallurgical dusts, the relative contributions of Fe2+/3+ ions in octahedral B sites and Fe2+ ions in tetrahedral A sites in magnetite spinel structure differs considerably.

Copper-ore mining in Sweden since the pre-Roman Iron Age: lake-sediment evidence of human activities at the Garpenberg ore field since 375 BCE.

Historical documents, archaeological evidence and lake-sediment records indicate thus far that significant mining of iron and copper ores in the Berglsagen mining region in central Sweden did not begin until the late 12th century – first with iron in Norberg – and thereafter spreading rapidly throughout the region during the 13th century when also copper was included (e.g. Falun). Prior to this, iron was produced domestically from secondary sources such as bog iron, while geochemical analyses of bronze artefacts indicate copper was imported. The parish of Garpenberg was at the intersection between historical iron- and copper-mining districts, and consequently we expected our sediment record from the lake Gruvsjön (‘mine lake’) to follow the established 13th century development. However, a 2–3-fold enrichment in copper and lead occurred already during 375–175BCE (pre-Roman Iron Age), together with small increases in zinc, magnesium and charcoal particles, and changes in pollen. Together these indicate a clear pattern of human disturbance connected with the ore body bordering the lake. A second distinct phase occurred 115–275CE, but with an 8–9-fold increase in copper and lead along with other indicators. From 400CE a permanent increase in copper and lead occurred, which then accelerated from the 13th century as seen elsewhere in the region. Our results push back the evidence for early ore mining in Sweden from the Middle Ages to the pre-Roman Iron Age.

Bladesmithing at South Dakota School of Mines and Technology

A Damascus-style layered blade was made by incorporating bloomery iron and crucible steel. A bloomery furnace was constructed and charged with Black Hills, SD bog iron ore, alloys, and hardwood charcoal. At sufficient temperature, the furnace was bottom-tapped to produce a low carbon iron bloom. A high-carbon crucible steel was made in a natural gas-fired furnace using commercial hematite pellets and coke. The steel was cast into sand molds. The two types of iron/steel were forged together using traditional blacksmithing techniques in a coke-fired forge. The forging process continued until the metal could be evenly worked, signifying the homogenization of the two metals. Once homogenized, the metal was shaped into a blade and subsequently ground into near-final shape, heat-treated, and finish-machined. The microstructure and mechanical properties of the blade were characterized using optical microscopy, hardness and tensile testing. The grain structure of the material varied widely and was not entirely homogenous at the welded layers, but the layers themselves were well-homogenized. The finished blade was compared to a common steel (1095) used for bladesmithing and was found to have similar hardness but significantly lower tensile strength.

The influence of bog iron ore roasting on its arsenic sorption properties and destabilization caused by presence of microorganisms

The influence of bog iron ore roasting on its arsenic sorption properties and destabilization caused by presence of microorganisms

FeO2 and FeOOH under deep lower-mantle conditions and Earth's oxygen-hydrogen cycles.

The distribution, accumulation and circulation of oxygen and hydrogen in Earth's interior dictate the geochemical evolution of the hydrosphere, atmosphere and biosphere. The oxygen-rich atmosphere and iron-rich core represent two end-members of the oxygen-iron (O-Fe) system, overlapping with the entire pressure-temperature-composition range of the planet. The extreme pressure and temperature conditions of the deep interior alter the oxidation states, spin states and phase stabilities of iron oxides, creating new stoichiometries, such as Fe4O5 (ref. 5) and Fe5O6 (ref. 6). Such interactions between O and Fe dictate Earth's formation, the separation of the core and mantle, and the evolution of the atmosphere. Iron, in its multiple oxidation states, controls the oxygen fugacity and oxygen budget, with hydrogen having a key role in the reaction of Fe and O (causing iron to rust in humid air). Here we use first-principles calculations and experiments to identify a highly stable, pyrite-structured iron oxide (FeO2) at 76 gigapascals and 1,800 kelvin that holds an excessive amount of oxygen. We show that the mineral goethite, FeOOH, which exists ubiquitously as 'rust' and is concentrated in bog iron ore, decomposes under the deep lower-mantle conditions to form FeO2 and release H2. The reaction could cause accumulation of the heavy FeO2-bearing patches in the deep lower mantle, upward migration of hydrogen, and separation of the oxygen and hydrogen cycles. This process provides an alternative interpretation for the origin of seismic and geochemical anomalies in the deep lower mantle, as well as a sporadic O2 source for the Great Oxidation Event over two billion years ago that created the present oxygen-rich atmosphere.

Geochemistry: Hydrogen and oxygen in the deep Earth.

The finding that an unusual iron oxide forms at extremely high pressures suggests that hydrogen and oxygen — two elements that strongly influence Earth's evolution — are generated in the mantle. See Letter p.241 First-principles calculations and direct experiments are used to identify a highly stable, pyrite-structured iron oxide at pressures and temperatures relevant to Earth's deep lower mantle. Ho-Kwang Mao and colleagues show that the mineral goethite (FeOOH), ubiquitous in nature as 'rust' and found in large quantities as bog iron ore, decomposes under such conditions to form FeO2 and release H2. The reaction could cause accumulation of the heavy FeO2-bearing patches in the deep lower mantle, upward migration of hydrogen and separation of the oxygen and hydrogen cycles. The authors conclude that the process provides an alternative interpretation for the origin of seismic and geochemical anomalies in the deep lower mantle, as well as a sporadic oxygen source for the Great Oxidation Event over 2 billion years ago that created the present-day oxygen-rich atmosphere

Bog iron ore as a resource for prehistoric iron production in Central Europe — A case study of the Widawa catchment area in eastern Silesia, Poland

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. This paper investigates the mineralogical and elemental composition of local bog iron ore deposits and iron slag finds, as a by-product of the smelting process, also taking into account the state of the art in research regarding the formation, distribution and utilization of bog iron ores and considering data from comparative studies.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 64.9mass% Fe2O3 (equivalent to 45.4mass% Fe), whereas the iron contents of bloomery slags vary between 48.7 and 72.0mass% FeO (equivalent to 37.9 and 56.0mass% Fe). A principal component analysis of the element contents, which were quantified by portable energy-dispersive X-ray fluorescence spectrometry, indicates local variations in the elemental composition. The results of this study show that bog iron ores are relatively widely distributed with spatially varying iron contents along the Widawa floodplain but present-day formation conditions, such as changed groundwater levels, are negatively affected by modern land-use practices, such as agriculture and melioration measures.

Rare earth elements and Rb–Sr and Sm–Nd systematics in the peat bog iron ore and moss of the NW East European Platform

Spectra of the REE distribution in the Quaternary–Recent peat bog ore of southern Karelia and Leningrad region are characterized by LaN/YbN < 1.0, presence of positive Eu and negative Ce anomalies, and higher Y enrichment (relative to Ho and Dy) because of the REE sorption by Fe-bearing minerals in acid boggy waters. The 87Sr/86Sr ratio is 0.7175 in iron oxyhydroxides of the Somino deposit (Leningrad region) and 0.7283 in the Polovinkino ore (southern Karelia). The 143Nd/144Nd ratio in them is 0.511844 and 0.511617, respectively.

Arsenic interactions with bog iron ores – As(III) and As(V) adsorption-desorption study [abstract

Arsenic interactions with bog iron ores – As(III) and As(V) adsorption-desorption study [abstract

Mineral transformations and textural evolution during roasting of bog iron ores

The processes occurring during roasting of bog iron ores were characterized using TG–DTG–DTA–QMS, XRD, FTIR and specific surface analysis. Removal of physically adsorbed water is followed by dehydroxylation of iron oxyhydroxides and oxidation of organic matter at 200–600 °C. The main product of the transformations is disordered nanocrystalline (proto)hematite or hematite/maghemite mixture, depending on organic matter content and heating conditions. The conversion of iron oxyhydroxides to hematite occurs at temperatures different than those reported for pure compounds. At higher temperatures, protohematite undergoes recrystallization to the stoichiometric hematite, and manganese oxides are partially reduced. At 1000 °C, the roasting products consist of hematite and cristobalite together with Mn–Fe spinels if the initial ore contained Mn oxides. The admixtures of various secondary silicates were encountered as well. Low- to moderate-temperature roasting slightly affects the specific surface area and lowers volume of micropores. The high-temperature transformations lead to decrease in the specific surface area and to the destruction of porous texture of the bog iron ores. Although the general course of the processes during roasting was similar in all the samples, some of their details as well as mineralogy and properties of the products are highly dependent on the composition of the initial material.

Microbes: mini iron factories.

Microbes have flourished in extreme habitats since beginning of the Earth and have played an important role in geological processes like weathering, mineralization, diagenesis, mineral formation and destruction. Biotic mineralization is one of the most fascinating examples of how microbes have been influencing geological processes. Iron oxidizing and reducing bacteria are capable of precipitating wide varieties of iron oxides (magnetite), carbonates (siderite) and sulphides (greigite) via controlled or induced mineralization processes. Microbes have also been considered to play an important role in the history of evolution of sedimentary rocks on Earth from the formation of banded iron formations during the Archean to modern biotic bog iron and ochre deposits. Here, we discuss the role that microbes have been playing in precipitation of iron and the role and importance of interdisciplinary studies in the field of geology and biology in solving some of the major geological mysteries.

Conservation of the Structure and Materials of Historic Masonry Walls

The paper presents a structural analysis, restoration programme and scope of conservation work essential for protecting historical values based on the example of an overstretched retaining wall providing support for the embankment of an heritage church. The focus was on analysing the status of an historic stone wall constructed in part with bog iron ore (metal ore or iron-rich sedimentary rock). Ore was used for iron smelting and also as a building material. Bog iron ore was frequently used in construction across Poland, especially in places where the raw material was locally available, aesthetically attractive and had mechanical properties approximating the durability of ceramic bricks. The material was characterised by high porosity, low resistance to diffusion and high resistance to freezing, which meant that it could be used successfully in structures subjected to atmospheric impacts without additional protection

Time changeability model of the bog ore sorption ability

Abstract Basing on long-standing cyclic measurements of sludge-originated biogas composition and considering statistical analysis of their results, a regression model describing time variation of biogas desulfurization using bog iron ore has been developed. The model was verified by theoretical calculations and results from laboratory examinations of the sorbent. It was also used to estimate the depletion time and sorption capacity of the bed and to determine the demand index for bog ore.