Lawn iron stone

Typical lawn iron stone concretion

As bog iron or bog iron are particularly high iron contents consolidations marked in recent as fossil groundwater soils indicated that rocks like as concretions or bank-like as soil horizons occur.

Basics

Turf iron stone is sediment fractions of the soil that have been solidified by iron minerals . These are mostly sand , clay and silt , sometimes gravel , and sometimes organic substrates (especially peat ) with high metal contents .

In these horizons, which are often up to half a meter thick, the iron content - the main minerals are represented by the limonite complex - can in rare cases be up to 66 percent by mass Fe. Manganese , partly phosphorus and other elements also play a role in many of these accumulations .

Lawn iron stone can be smelted for iron production , although its iron content is lower than that of other iron ores.

Designations

Pieces of lawn iron from near Żyrardów , Poland

The name lawn iron stone comes from the fact that it is located close to the sod in groundwater soils and can easily be extracted with a spade and hoe. Other names for sometimes as slag appearing red-brown to (at higher manganese contents) blue-black consolidations are limonite , marsh Eisenstein , swamp bog iron or simply Rasenerz or bog .

Turf iron stone must not be confused with its main mineral component limonite, which is also known as brown iron stone or ore . Further possibilities of confusion of a conceptual nature exist with the iron mineral siderite called clay or spate iron stone , with the rock iron sandstone , the Ortstein or the Orterde of Podsolen as well as with floor ore . Turf iron earth is the term used to describe largely non-solidified accumulations in gley soils , which can be a preliminary stage for the development of the turf iron stone.

Emergence

Ferrous, boggy water

Dry stone wall made of pieces of lawn iron

Lawn iron stone can be created in different ways. Redox processes are always essential , sometimes involving microorganisms ( bacteria , for example Acidithiobacillus ferrooxidans ). In the fluctuation range of the groundwater , in which iron and manganese salts are dissolved ( leachate only plays a subordinate role here), oxidic / hydroxidic iron and manganese compounds precipitate on contact with oxygen (see ocher formation ). Pronounced lawn iron stone formations are often due to slight fluctuations in the groundwater level when the water is very iron-rich. The period of origin of Raseneisenstein usually extends over hundreds to thousands of years, depending on the occurrence.

Turf iron stone is particularly common in the Go von Gleyen oxidation horizon. According to the pedological mapping instructions , go horizons with brown iron present as lawn iron stone concretion are referred to as Gkso and those with banked lawn iron stone as Gmso . From a certain thickness and the typical solid shape, these horizons are also called RES for short . Turf iron stone can also form in gleypodsoles and moor soils .

During the Holocene , after the last Ice Age , veritable lawn iron ore deposits emerged in northern Germany . They were mainly formed in floodplains in fine to medium-grain sands through which ferrous groundwater flows . These soils, which are impermeable to the roots from the Raseneisenstein, are only considered to be of arable land use to a limited extent and can generally only be used as meadow or pasture land.

During the cold periods of the Pleistocene in southern Germany the training of bog iron in the warmer was permafrost free interstadials possible. For example, the gravel bodies of the Rhine terraces in the lower Middle Rhine lead to very manganese-rich iron stone horizons. These are often tied to powerful sloping bodies. These concretions indicate fossil, i.e. earlier, groundwater levels and are therefore also distributed over the entire profile and are not only found near the top of the terrain.

Occurrence and protection

Raseneisenstein occurs worldwide mainly in the moderate latitudes , especially in damp and swampy lowlands . Depending on the climate and the landscape, this mainly affects northern central and southern northern Europe . A strip of extensive deposits running from Hamburg through the center of Schleswig-Holstein to Flensburg has been archaeologically examined. After the Thirty Years War , the deposits in the northern part of Brandenburg were used economically (see section iron extraction ).

There are recent deposits that are still close to the earth's surface today, as well as fossil deposits that have been buried or covered over time by further layers of soil or rock. Generally only the latter are dealt with in the specialist geological literature.

Formerly significant Central European deposits are largely considered to be mined. Most of the time only marginal remains or small or small-scale sites of the old deposits are left that are not economically recoverable. Occurrences of larger chunks that can be used as building material, which are required, for example, to repair historical and listed buildings made of lawn iron stone, have become rare.

Some turf iron stone residues and low soils with current iron oxide precipitation are now in Germany - as a result of the Federal Soil Protection Act - because of their rarity and their archival function, which is important in terms of natural and cultural history, as "priority areas for soil protection ", mostly at the local level.

Place and field names

The presence and use of bog iron were - similar to iron ore - direct its name to numerous places and place names , especially with the name component -eisen- in Germany among other Isernhagen and Iserbrook ( Isern "iron"), iron Hausen, Eisemroth (both in Central Hesse) and Jerrishoe ( Danish jern "iron") as well as for several places with the name component -hütten- (from smelting). In East Germany, where many place and field names are of Slavic origin, the syllable Rud- (e.g. Berlin-Rudow ) is synonymous .

use

Elisabeth Church in Langenhagen . The lower part of the church tower is made of lawn iron stone.

House made of iron stone in Bresegard near Eldena , Mecklenburg

Nicolaikirche in Hannover-Bothfeld . The church tower consists entirely of lawn iron stone.

Iron extraction

Lawn iron stone with iron concentrations from about 55–60 percent by mass Fe has been extracted as iron ore in Central and Northern Europe since the Iron Age and smelted in racing furnaces .

The lawn iron stone was of considerable importance for Brandenburg-Prussia for several hundred years. The ironworks , which was documented in Zehdenick as early as the 15th century , was rebuilt by the Great Elector in 1664–1666 in order to have mostly cannonballs cast in it.

In the 19th century, the regional turf iron stone deposits on the Lower Rhine were used for iron extraction in the absence of other sources.

The heavy industry in the Ruhr area last used regional turf iron stone deposits in the Emscherniederung during World War II as a substitute for the richer iron ores otherwise used.

Building material

Lawn iron stone and brick in combination at the village church Alt-Lönnewitz

The easily workable lawn iron stone was used as a building material . However, only “stones” that are particularly rich in metal are suitable for this, as material with a low iron content is relatively brittle and has a very low resistance to weathering . Iron-rich, hard and, due to its pores, good heat-insulating turf iron stone was mainly used in the rock-poor lowland regions of Central Europe for the construction of walls, foundations and buildings. Lawn iron stone as a building material was already used by the Vikings , so from 989 to 1020 on the coast of Newfoundland in their settlement in Helluland (flagstone country), today L'Anse aux Meadows .

Examples:

the city wall of the Brandenburg town of Dahme , consisting largely of lawn iron stone and therefore called the "Iron Wall",
old houses (club houses) and churches in parts of Mecklenburg-Western Pomerania , which were built entirely from the lawn iron stone called "Klump", typical; u. a. the Redefin stud and various houses in southwest Mecklenburg such as in Wöbbelin or Grebs-Niendorf ,
the city wall and the pylon-like bell towers of the city church of Ludwigslust ,
the towers of the Evangelical Lutheran churches of St. Nicolai (Hanover-Bothfeld) , St. Osdag in Mandelsloh and in Winsen (Aller) on the southern edge of the Lüneburg Heath ,
the first burnt down building of the Verden Cathedral .
The Bärwinkel Vorwerk in Neuhardenberg from 1803, one of the first works by the later famous master builder Carl Friedrich Schinkel .

Because of its rustic structure, lawn iron stone was used in some engineering structures in the Dessau-Wörlitz Garden Realm , especially in Wörlitz Park . Particularly noteworthy is the construction group named after the typical landscape name of the lawn iron stone "Eisenhardt". The so-called “stone”, a miniature replica of Vesuvius , as well as bridges and tunnel systems in the park were also built with lawn iron stone for the sake of effect. Outside the park, the "Rauhe Wachhaus" on Fliederwall between Vockerode and Wörlitz should be mentioned. In the New Potsdam Garden, partly based on the Wörlitz model, the facade cladding of the shell grotto consists partly of lawn iron stone.

Furthermore, lawn iron stone is occasionally used in the fine arts as a natural design element.

literature

Wolfgang Koschke: Lawn iron ore and ironworks industry in northern Upper Lusatia (= contributions to the history of the town and park in Bad Muskau , volume 18), Friends of the town and park museum, Bad Muskau 2002 OCLC 249383789 , (40 pages).

Wolfgang Koschke: Muskauer Eisen: iron production in the Muskau estate , Friends of “Historica” Bad Muskau eV, Oetel, Görlitz 2012, ISBN 978-3-938583-90-6 .

Armin Graupner: Lawn iron stone in Lower Saxony. Origin, occurrence, composition and use (= publications of the Lower Saxony Institute for Regional Studies and Regional Development at the University of Göttingen ; Volume 118, publications of the Economic Society for the Study of Lower Saxony eV NF) Göttinger Tageblatt, Göttingen / Hanover 1982, DNB 830113991 (180 pages).

Michael Ganzelewski: The early smelting of lawn iron ores on the Kammberg near Joldelund (Schleswig-Holstein). Bochum 1997, DNB 956956076 (Dissertation University of Bochum 1998, 120 pages, 3 microfiches 24x).

Dieter Beeger: Two unusual types of natural stone - brown coal quartzite and lawn iron ore. In: natural stone . 6/97 (52nd year). Pp. 68-70. Ulm 1997.

Udo Scheer: Lawn iron ore as a raw material. In: Detlef Hopp, Charlotte Trümpler (ed.): The early Roman Empire in the Ruhr area. Klartext, Essen 2001, pp. 121–127, ISBN 3-89861-069-1 .

Franz Joachim Ernst: The prehistoric iron production (= messages of the district committee for prehistory and early history Neubrandenburg . Issue 14). Deutscher Kulturbund, Neubrandenburg 1966 (93 pages, in it: map and catalog of the lawn iron ore deposits in Mecklenburg-Western Pomerania).

MLUR, Section Soil Protection: Gley with lawn iron soil . (pdf, 7.2 MB) Characteristics of Brandenburg Floors, No. 9.5. Ministry of Agriculture, Environmental Protection and Regional Planning of the State of Brandenburg (ed.). Brandenburg. 2003.

Frank Schlütter: DBU project Raseneisenstein: results of the MPA Bremen. 1998–99 reporting period . (pdf, 3.7 MB) Free Hanseatic City of Bremen, Official Materials Testing Institute. 2000.

R. Hillenkamp: Turf iron ore: a forgotten natural resource in our region too . In: Heimatbuch für die Landkreis Teltow-Fläming, Vol. 13, Berlin: 2006, pp. 34–37.

H. Döbling: Lawn iron ore for the Sterkrader huts . In: Heimatkalender Kreis Dinslaken , vol. 25, Dinslaken: 1968, pp. 80–87.

Sabine Bock : Lawn iron stone as a building material for rural buildings in southwest Mecklenburg . In: Preserving and building in the country. Working material for the 1st Central Conference on Folk Building in the GDR. Leipzig 1985, pp. 95-100.

Sabine Bock : Building with “Klump” . In: Schweriner Blätter. Vol. 7, 1987, pp. 16-19.

Act on the mining of lawn iron ore of June 22, 1937

Web links

Commons : Raseneisenstein - collection of images

Individual evidence

^ I. Joosten, JBH Jansen, H. Kars: Geochemistry and the past: Estimation of the output of a Germanic iron production site in the Netherlands. Journal of Geochemical Exploration. Vol. 62, No. 1-3, 1998, pp. 129-137, doi: 10.1016 / S0375-6742 (97) 00043-5 .
↑ Friedrich Lenz, Otto Unholtz: The history of the bank Brothers Schickler. G. Reimer Verlag, Berlin 1912 ( archive.org ), pp. 26-30.
↑ Heather Pringle: When the Vikings were in America . National Geographic, issue 11/2012, pp. 74-87 ( HTML version ).
↑ Gottfried Kiesow : Ways to Brick Gothic, An Introduction . 2nd Edition. Monuments publications of the German Foundation for Monument Protection, Bonn 2007, ISBN 978-3-936942-34-7 , p. 63 .

[1] I. Joosten, JBH Jansen, H. Kars: Geochemistry and the past: Estimation of the output of a Germanic iron production site in the Netherlands. Journal of Geochemical Exploration. Vol. 62, No. 1-3, 1998, pp. 129-137, doi: 10.1016 / S0375-6742 (97) 00043-5 .

[2] Friedrich Lenz, Otto Unholtz: The history of the bank Brothers Schickler. G. Reimer Verlag, Berlin 1912 ( archive.org ), pp. 26-30.

[3] Heather Pringle: When the Vikings were in America . National Geographic, issue 11/2012, pp. 74-87 ( HTML version ).

[4] Gottfried Kiesow : Ways to Brick Gothic, An Introduction . 2nd Edition. Monuments publications of the German Foundation for Monument Protection, Bonn 2007, ISBN 978-3-936942-34-7 , p. 63 .