Harz granite
Encyclopedia
Harz granite is found in the Harz Mountains of central Germany. It may be divided into five types, all of which were widely used as natural stone: Knaupsholz granite, Birkenkopf granite, Wurmberg granite, Königskopf granite and Ilsestein granite. The first three granite
s were widely used in North Germany, Belgium and the Netherlands and, later, also in East Germany. Knaupsholz granite was "for a long time one of the most important types of cut stone in the former GDR".
In 2009 only Knaupsholz granite was still being quarried.
s of the Harz Mountains - the Brocken, Ramberg and Oker plutons - were formed at the end of the Harz mountain building period (the Hercynian orogeny) during the Late Carboniferous about 300 million years ago. These natural stones were formed when large magma intrusions in the Brocken granite massif solidified at different cooling and crystallization rates into several differently coloured granites. The Harz granites are part of the Brocken granite complex, which is the largest granite complex in the Harz with an area of 165 sqkm. The Harzburg gabbro
-norite
intrusion forms part of this complex, but has a primary chemistry similar to an island-arc tholeiite
, although it shows the effects of large scale assimilation of crustal rocks.
(100 to 110 employees), Hannoversche Basaltwerke mbH with its branch, the Wernigerode Granite Quarries (Granitsteinbrüche Wernigerode, 60 to 70 employees), and Braunlager Granit- und Schotterwerke G.m.b.H. (45 employees). There were also 5 to 7 medium and 15 to 17 small businesses with a combined total of 600 employees. Their market at that time comprised the entire territory of the German Reich, Belgium and the Netherlands.
In 1948, after the war, 30 to 40 quarrymen were working in the Braunlager Granit- und Schotterwerken as well as an unknown number in another firm in Lower Saxony
. There are no exact figures for the numbers of workers in the firms of the German Democratic Republic
(GDR). The Knaupsholz and Birkenkopf quarries in the GDR and the divisions of the Zureck company in Wernigerode were expropriated on 5 November 1945.
In the early 1950s, the following quarries in the Brocken granite region were listed by Sickenberg (1951): Eckerloch, Schneeloch, Gebbertsberg, Wurmberg, Haserode, Wolfklippen, Großer und Kleiner Birkenkopf, Knaupsholz, Ottofels, Neustätter Hau, Forsthaus Plessenburg and Gelochter Stein. In 1958, eight quarries were still being worked in the territory of the GDR, but only two were left in 1969 (Knaupsholz and Birkenkopf).
and Schierke
, a kilometre east of Schierke station
in Saxony-Anhalt
. Knaupsholz granite was one of the most important building stones in East Germany.
, 45.9 % alkali feldspar
, 15.1 % plagioclase feldspar, 4.8 % biotite
and chlorite
, 0.7 % ore minerals, like magnetite
, pyrite
, hematite
, and 0.7 others. The alkali feldspar crystals can be up to 18 mm across.
. It is a medium-grained granite with blue-grey coloration. In the quarry 30 to 40 % blocks of stone could be used for sawing and 50 % of exploitable rock debris could be obtained. The quarry closed in 2009.
, pyrite
and hematite
.
and 250 metres high on the Wurmberg
mountain. The granite was pale red and fine to coarse-grained. The quarry has been closed since spring 1974.
, apatite
, rutile
, muskovite and opaque minerals.
. It was only of local significance, because it had low hardness.
of the Ilsestein granite was probably the last magma intrusion in the Brocken complex. It is the most quartz-rich granite in the Brocken complex. Its quartz and orthoclase elements grew together. Its utility and hardness as a construction stone is reduced by the numerous geode
s, up to 5 cm across.
Harz granites are weather-resistant, polishable and resistant to aggressive, chemical compounds. Their technical properties make them very suitable for outdoor use, but they are also used indoors due to their appearance.
These granites are used as solid building stones for bridge construction, walls, door lintels and window sills, staircase steps, flags, façades, gravestones and, as cobbles and hard core, for roads. Knaupsholz granite is used as stone chippings for trails in the Harz National Park
. In 2009, the remaining quarries at Knaupsholz and Birkenkopf (now closed) were providing granite for the following purposes:
s.
, Ravensbrück
and Sachsenhausen concentration camp
s; the Soviet War Memorial in Berlin's Tiergarten
and the Soviet Cenotaph in Treptow
; interior of the Schiller Museum in Weimar
; the mining church in Schierke; the Palace of Culture
of the GDR; the Deutsche Bank and town hall steps in Wernigerode.
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
s were widely used in North Germany, Belgium and the Netherlands and, later, also in East Germany. Knaupsholz granite was "for a long time one of the most important types of cut stone in the former GDR".
In 2009 only Knaupsholz granite was still being quarried.
Geology
The granitic plutonPluton
A pluton in geology is a body of intrusive igneous rock that crystallized from magma slowly cooling below the surface of the Earth. Plutons include batholiths, dikes, sills, laccoliths, lopoliths, and other igneous bodies...
s of the Harz Mountains - the Brocken, Ramberg and Oker plutons - were formed at the end of the Harz mountain building period (the Hercynian orogeny) during the Late Carboniferous about 300 million years ago. These natural stones were formed when large magma intrusions in the Brocken granite massif solidified at different cooling and crystallization rates into several differently coloured granites. The Harz granites are part of the Brocken granite complex, which is the largest granite complex in the Harz with an area of 165 sqkm. The Harzburg gabbro
Gabbro
Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
-norite
Norite
Norite is a mafic intrusive igneous rock composed largely of the calcium-rich plagioclase labradorite and hypersthene with olivine. Norite is essentially indistinguishable from gabbro without thin section study under the petrographic microscope...
intrusion forms part of this complex, but has a primary chemistry similar to an island-arc tholeiite
Tholeiite
The tholeiitic magma series is one of two main magma series in igneous rocks, the other magma series being the calc–alkaline. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it...
, although it shows the effects of large scale assimilation of crustal rocks.
Quarries
Among the large quarrying concerns operating before the Second World War in 1938 were the firms of Zureck in WernigerodeWernigerode
Wernigerode is a town in the district of Harz, Saxony-Anhalt, Germany. Until 2007, it was the capital of the district of Wernigerode. Its population was 35,500 in 1999....
(100 to 110 employees), Hannoversche Basaltwerke mbH with its branch, the Wernigerode Granite Quarries (Granitsteinbrüche Wernigerode, 60 to 70 employees), and Braunlager Granit- und Schotterwerke G.m.b.H. (45 employees). There were also 5 to 7 medium and 15 to 17 small businesses with a combined total of 600 employees. Their market at that time comprised the entire territory of the German Reich, Belgium and the Netherlands.
In 1948, after the war, 30 to 40 quarrymen were working in the Braunlager Granit- und Schotterwerken as well as an unknown number in another firm in Lower Saxony
Lower Saxony
Lower Saxony is a German state situated in north-western Germany and is second in area and fourth in population among the sixteen states of Germany...
. There are no exact figures for the numbers of workers in the firms of the German Democratic Republic
German Democratic Republic
The German Democratic Republic , informally called East Germany by West Germany and other countries, was a socialist state established in 1949 in the Soviet zone of occupied Germany, including East Berlin of the Allied-occupied capital city...
(GDR). The Knaupsholz and Birkenkopf quarries in the GDR and the divisions of the Zureck company in Wernigerode were expropriated on 5 November 1945.
In the early 1950s, the following quarries in the Brocken granite region were listed by Sickenberg (1951): Eckerloch, Schneeloch, Gebbertsberg, Wurmberg, Haserode, Wolfklippen, Großer und Kleiner Birkenkopf, Knaupsholz, Ottofels, Neustätter Hau, Forsthaus Plessenburg and Gelochter Stein. In 1958, eight quarries were still being worked in the territory of the GDR, but only two were left in 1969 (Knaupsholz and Birkenkopf).
Occurrence
Knaupsholz granite was quarried in the Knaupsholz forest district near the small settlements of Drei Annen HohneDrei Annen Hohne
Drei Annen Hohne is a village that lies on the edge of the Harz National Park in the Harz mountains of central Germany. Administratively it is part of the borough of Wernigerode in the district of Harz within the German state of Saxony-Anhalt....
and Schierke
Schierke
Schierke is a village and a former municipality in the Harz district, in the German state of Saxony-Anhalt. Since 1 July 2009, it is part of the town Wernigerode.Schierke was first mentioned as Schiriken in a 1590 deed...
, a kilometre east of Schierke station
Schierke station
Schierke station is the railway station in the village of Schierke operated by the Harz Narrow Gauge Railways on the Brocken Railway in the Harz Mountains of central Germany...
in Saxony-Anhalt
Saxony-Anhalt
Saxony-Anhalt is a landlocked state of Germany. Its capital is Magdeburg and it is surrounded by the German states of Lower Saxony, Brandenburg, Saxony, and Thuringia.Saxony-Anhalt covers an area of...
. Knaupsholz granite was one of the most important building stones in East Germany.
Mineral content
Knaupsholz granite is grey-red in colour and coarse-grained. It contains 33.5 % quartzQuartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, 45.9 % alkali feldspar
Alkali feldspar
The alkali feldspar group are those feldspar minerals rich in the alkali elements like potassium. The alkali feldspars include: anorthoclase, microcline, orthoclase and sanidine....
, 15.1 % plagioclase feldspar, 4.8 % biotite
Biotite
Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula . More generally, it refers to the dark mica series, primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous endmembers...
and chlorite
Chlorite group
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the following four elements in the silicate lattice; Mg, Fe, Ni, and Mn....
, 0.7 % ore minerals, like magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
, and 0.7 others. The alkali feldspar crystals can be up to 18 mm across.
Occurrence
Birkenkopf granite was quarried on the Großer Birkenkopf hill south of HasselfeldeHasselfelde
Hasselfelde is a town in the district of Harz, in Saxony-Anhalt, Germany. It is situated in the eastern Harz, approximately 17 km south of Wernigerode. Since 1 January 2010, it is part of the town Oberharz am Brocken...
. It is a medium-grained granite with blue-grey coloration. In the quarry 30 to 40 % blocks of stone could be used for sawing and 50 % of exploitable rock debris could be obtained. The quarry closed in 2009.
Mineral composition
Birkenkopf granite contains 31.3 % quartz, 42.6 % alkali feldspar, 20.4 % plagioclase feldspar, 5.4 % biotite and chlorite as well as 0.3 % ore minerals like magnetiteMagnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
and hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
.
Occurrence
The quarry for Wurmberg granite was situated about 2.5 kilometres north of BraunlageBraunlage
Braunlage is a town and health resort in the Goslar district in Lower Saxony in Germany. It lies within the Harz mountain range, south of the Brocken.Nowadays Braunlage's main business is tourism, particularly ski tourists...
and 250 metres high on the Wurmberg
Wurmberg
Wurmberg is a town in the district of Enz in Baden-Württemberg in Germany....
mountain. The granite was pale red and fine to coarse-grained. The quarry has been closed since spring 1974.
Mineral composition
This granite contains 31 % quartz, 42 % alkali feldspar, 20 % plagioclase feldspar, 7 % biotite, as well as less than 1 % of other minerals like zirconZircon
Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...
, apatite
Apatite
Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...
, rutile
Rutile
Rutile is a mineral composed primarily of titanium dioxide, TiO2.Rutile is the most common natural form of TiO2. Two rarer polymorphs of TiO2 are known:...
, muskovite and opaque minerals.
Occurrence
Königskopf granite was extracted in a quarry near Königskrug, which closed in the 1960s. As a result of ecological restrictions it is unlikely to be reopened again. The granite is light red to intense red (flesh red) in colour.Mineral composition
Königskopf granite contains 33 % quartz, 42 % orthoclase with a mineral grain size of 2 to 5 mm up to a maximum of 15 mm, 22 % plagioclase feldspar, 5 % biotite and 0.7 % other minerals.Ilsestein granite
Ilsestein granite was quarried on the northern boundary of the Harz on the Kleiner Birkenkopf hill near ThaleThale
Thale is a town in the Harz district in Saxony-Anhalt in central Germany.-Geography:It is situated on the river Bode, approximately 8 km west of Quedlinburg. It is the terminus of the Magdeburg–Thale railway.- History :...
. It was only of local significance, because it had low hardness.
Geology and occurrence
Ilsestein granite lies on the northern perimeter of the Harz and is part of the Brocken massif. It occurs in a vein-like deposit, 11 kilometres long and 2 kilometres wide. The magmaMagma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
of the Ilsestein granite was probably the last magma intrusion in the Brocken complex. It is the most quartz-rich granite in the Brocken complex. Its quartz and orthoclase elements grew together. Its utility and hardness as a construction stone is reduced by the numerous geode
Geode
Geodes are geological secondary sedimentary structures which occur in sedimentary and certain volcanic rocks. Geodes are essentially spherical masses of mineral matter that were deposited sygenetically within the rock formations they are found in. Geodes have a Chalcedony shell containing...
s, up to 5 cm across.
Use
These granites are used as solid building stones for bridge construction, walls, door lintels and window sills, staircase steps, flags, façades, gravestones and, as cobbles and hard core, for roads. Knaupsholz granite is used as stone chippings for trails in the Harz National Park
Harz National Park
The Harz National Park is a nature reserve in the German federal states of Lower Saxony and Saxony-Anhalt. It comprises large portions of the western Harz mountain range, extending from Herzberg and Bad Lauterberg at the southern edge to Bad Harzburg and Ilsenburg on the northern slopes...
. In 2009, the remaining quarries at Knaupsholz and Birkenkopf (now closed) were providing granite for the following purposes:
Technical construction
Road surfaces, cobbles, walls and bridges in Lower Saxony and North Germany, Magdeburg, Hamburg and Berlin; lock construction and bank reinforcement on the Mittelland and Kiel CanalKiel Canal
The Kiel Canal , known as the Kaiser-Wilhelm-Kanal until 1948, is a long canal in the German state of Schleswig-Holstein.The canal links the North Sea at Brunsbüttel to the Baltic Sea at Kiel-Holtenau. An average of is saved by using the Kiel Canal instead of going around the Jutland Peninsula....
s.
Monuments and buildings
Harz granite has been used for monuments and memorials in BuchenwaldBuchenwald concentration camp
Buchenwald concentration camp was a German Nazi concentration camp established on the Ettersberg near Weimar, Germany, in July 1937, one of the first and the largest of the concentration camps on German soil.Camp prisoners from all over Europe and Russia—Jews, non-Jewish Poles and Slovenes,...
, Ravensbrück
Ravensbrück concentration camp
Ravensbrück was a notorious women's concentration camp during World War II, located in northern Germany, 90 km north of Berlin at a site near the village of Ravensbrück ....
and Sachsenhausen concentration camp
Sachsenhausen concentration camp
Sachsenhausen or Sachsenhausen-Oranienburg was a Nazi concentration camp in Oranienburg, Germany, used primarily for political prisoners from 1936 to the end of the Third Reich in May, 1945. After World War II, when Oranienburg was in the Soviet Occupation Zone, the structure was used as an NKVD...
s; the Soviet War Memorial in Berlin's Tiergarten
Soviet War Memorial (Tiergarten)
The Soviet War Memorial is one of several war memorials in Berlin, capital city of Germany, erected by the Soviet Union to commemorate its war dead, particularly the 80,000 soldiers of the Soviet Armed Forces who died during the Battle of Berlin in April and May 1945.The memorial is located in the...
and the Soviet Cenotaph in Treptow
Soviet War Memorial (Treptower Park)
The Soviet War Memorial, is a vast war memorial and military cemetery in Berlin's Treptower Park. It was built to the design of the Soviet architect Yakov Belopolsky to commemorate 5,000 of the 80,000 Soviet soldiers who fell in the Battle of Berlin in April–May 1945...
; interior of the Schiller Museum in Weimar
Weimar
Weimar is a city in Germany famous for its cultural heritage. It is located in the federal state of Thuringia , north of the Thüringer Wald, east of Erfurt, and southwest of Halle and Leipzig. Its current population is approximately 65,000. The oldest record of the city dates from the year 899...
; the mining church in Schierke; the Palace of Culture
Palace of Culture
Palace of Culture or House of Culture was the name for major club-houses in the former Soviet Union and the rest of the Eastern bloc. It was an establishment for all kinds of recreational activities and hobbies: sports, collecting, arts, etc., and the Palace of Culture was designed to have room...
of the GDR; the Deutsche Bank and town hall steps in Wernigerode.