Mining in the Upper Harz
Encyclopedia
Mining in the Upper Harz region of central Germany was a major industry for several centuries, especially for the production of silver, lead, copper, and, latterly, zinc as well. Great wealth was accumulated from the mining of silver from the 16th to the 19th centuries, as well as from important technical inventions. The centre of the mining industry was the group of seven Upper Harz
mining town
s of Clausthal, Zellerfeld
, Sankt Andreasberg
, Wildemann
, Grund
, Lautenthal
und Altenau
.
Its lucrativeness justified a high commitment in terms of investment and effort. The Upper Harz mining industry produced a considerable number of innovations and inventions, including such important advances as the man engine
, the water-column engine and the wire cable.
In the Upper Harz, vein mining (Gangerzbergbau) predominated. Excavation followed the almost vertically standing lodes or veins (Erzgängen) downwards. In their heyday the Upper Harz Mines were among the deepest in the world. For example, as early as 1700 or so shafts were already exceeding depths of 300 metres and, around 1830, a depth of 600 metres was achieved – which was considered significant at that time because it was below sea level.
. At that time mining, including this early use of water systems, was carried out by the Cistercian abbey of Walkenried
. At first outcropping lodes on the surface of the ground were sought out and sections of ore near the surface were dug out with hammers and chisels. Mining first boomed between 1200 and 1360. In the upper workings there were particularly rich veins of silver ore (up to 9% Ag).
Plague
epidemics during the Middle Ages
depopulated the Harz to a great extent and almost brought mining operations to a standstill. Another factor was probably that mining had reached its technical limits at the time with depths of up to about 60 m.
. But it was his son, Julius, Duke of Brunswick-Lüneburg
, who gave added impetus to existing mining operations in the Upper Harz and initiated the creation of further infrastructure, especially the structures of the Upper Harz Water Regale
to provide water power for the mines. In order to entice the necessary labourers, tradesmen and even mining companies to the Harz, the dukes granted 'mining freedoms' (Bergfreiheiten) based on Bohemian and Saxon practice.
Because considerable energy was needed to dewater the mines and the consumption for this grew as the mines became deeper and deeper, attempts were made early on to reduce energy consumption by driving drainage adits. This entailed cutting tunnels from the mine into the neighbouring valleys, through which water could drain away downhill under gravity. The deeper the dewatering level lay, the longer these adits needed to be. The longest of these tunnels was the Ernst August Tunnel, built in the mid-19th century, which was 26 kilometres long. It collected water from the mines in Bockswiese, Lautenthal, Zellerfeld, Clausthal and Wildemann and transported it to Gittelde
on the edge of the Harz.
The Upper Harz mines attained their greatest lucrativity in the 16th and 17th centuries, even though there were frequent crises during that time. In 1690 the metal produced reached a quantity that was not exceeded until 1850. That was especially thanks to the construction of artificial water supply structures and the introduction of gunpowder
for rock blasting
from 1630 onwards. During the course of the 18th century there were constant crises as a result of the lack of wood. The problem was eased by the introduction of coking coal for the smelters around 1800. On 1 January 1864 the mines were nationalised by the Kingdom of Hanover
.
in 1866 the Royal Prussian Mining Inspectorate (Königlich-Preußische Bergbauinspektion) took over the running of mines in the Upper Harz. It was succeeded in 1924 by Preussag
. Around 1900 shaft depths of 1,000 metres were reached and the mining of ore became increasingly costly. At the same time the mines had to compete with other domestic and foreign mines in a climate of ever-improving transportation. Overexploitation during the First World War and plummeting metal prices resulted in major closures at the height of the Great Depression
in 1930, when the big mines around Clausthal-Zellerfeld
, Bockswiese and Lautenthal
had to close. Mining operations continued in Bad Grund, however, until 1992.
were driven to produce electricity at the level of the deepest drainage adit. The generation of electricity was carried out by Preussag until 1980 in the Kaiser Wilhelm (maximum output 4.5 MW) and Ottiliae (maximum output 1.5 MW) shafts. The hydropower stations were closed in the early 1980s when the water rights expired and the profitability of the power stations continued to fall at a time of sharply rising wages and stagnating electricity prices. These years saw the permanent closure of the last surviving mines.
. With increasing depth a form of mixed mining developed that was somewhere between open cast and underground mining. These mines were known as glory holes (Pingen) or simply dip mines (Unterwerksbau). The ore deposits that lay immediately on the surface were quickly exhausted and, as early as the 12th and 13th century miners were forced to switch entirely over to underground mining. The mining methods that could be used were limited by the steep, almost vertical, lenticles
of ore, which were only a few metres wide, but dipped for several hundred metres into the earth. Hauling shafts were usually positioned in centre of the ore allotment on the lode and followed it into the ground. This resulted in inclined shafts with their characteristic, right-angled, longitudinal sections and frequent changes of angle away from the vertical. There were two reasons for this approach: firstly, it had to be possible to extract ore from the beginning (as soon as the shaft was sunk) in order to make the pit economical as early as possible. Secondly, the rock in the ore lode, which formed a 'zone of disturbance', was much softer than the surrounding rock. The typical Harz grauwacke was far harder than concrete. As a result the majority of drainage adits followed the vein. From the shaft, main gangways, the so-called Feldortstrecken, were driven out to the boundary of the mine allotment. From these gangways, miners began to extract the ore, heading downwards into the floor, by 'brushing down' (Nachreißen) in stepped fashion, a technique known as underhand stoping. The stope
s had a height of up to 3 metres and followed one another about 5 to 6 metres apart. In longitudinal section, therefore, a pit looked like a Christmas tree standing on its head. The deepest point of the pit was usually the main shaft. This enabled it to collect pit water in the shaft 'sump'. As mining progressed the shaft was sunk deeper.
The packing (gangue material used for filling) from the upper main gangways was placed in the exhausted cavities (the so-called 'old man' or Alter Mann). This required the erection of a wooden ceiling over the active workings so that packing material did not fall into it and onto the face workers there. If the expected supply of ore or its quality did not justify sinking the main shaft deeper, or if the workings were a long way from it, draw-shafts were sunk. These blind shafts saved having to pack the 'old man'. In the Hornstatt, 1 or 2 labourers (Knechte) worked a hand winch
and lifted the ore to the next highest main gallery.
From 1633 gunpowder
was used both for ore extraction and for driving gangways. This increased the daily headway considerably, from a few centimetres into the lode to a metre or more. The disadvantage, however, was that even more wood was needed to extend the mine, because blasting
caused the rock to fissure. When blasting, first a cut in the lode was made about 3 metres high and deep and a little less than a metre wide using hammer and chisel. Next one or two transverse boreholes with a 6–7 cm diameter were drilled by hand Usually two-man boring was employed: one turned the borer whilst a second hit it with his sledge. The holes were filled with gunpowder and stuffed with a wooden peg which had a hole for a slow-match wick. Unlike blasting with modern explosive, the stemming had to be wedged in using an iron rod centred on the borehole and a thick wooden prop in a slot (Bühnloch) on the opposite side. This operation frequently led to serious accidents when the gunpowder self-ignited as a result of friction-generated heat. Normal detonation was carried out using cord that had been impregnated with sulphur and gunpowder.
After clearing the blast debris, the material to be screened was loaded into wagons (Hunde or Hunte) using rakes (Kratze) and tubs (Trog). Larger boulders (Wände) were first broken up with sledges and crowbars.
From the second half of the 18th century the method of mining was reversed. Now the roof was always mined and so extraction proceeded upwards. That meant the miners worked on top of the packing and could transport the ore under gravity using so-called chute holes (Rollöcher or Rollen) rather than shafts. Overhand stoping remained the only mining method in the Upper Harz mines until the end and was perfected in the final years through the use of trackless wagons, roof bolts
(Ankern), shotcrete
and lean concrete
packing. Trials with sublevel stoping (Teilsohlenbruchbau) and square set timbering (Blockbau mit Rahmenzimmerung) did not get past the experimental stage.
In the middle of the 19th century, the many individual pits transferred to larger mine complexes with central shafts, at which point the sinking of inclined shafts and the mixing of layout and equipment with the workings was abandoned entirely. The central, vertical shafts lay in the host rock (usually in the hanging wall), just as permanently established as the main gangways (usually in the footwall).
, a winch that was driven by the horses walking in a circle. The hauling cable (made of natural fibre) or cast-iron chain was wound up and down over a vertical axle. The cable was routed down the shaft and hauled barrels of ore up and down. Due to the shaft's incline, barrels were covered with iron runners on one side, resting partly on the side of the shaft. Above ground at the pithead the ore was emptied out and transported away by horse and cart for processing. From the 18th century shaft depths of several hundred metres were being achieved and horse whims were reaching the limits of their capability. Where the mines were lucrative and their energy consumption high as a result of shaft depth or the ingress of water, water power had been used since the 16th century. Water wheel
s (Kunsträder) drove piston pump
s in order to keep the mine dewatered (zu Sumpfe). Reversible water wheels (Kehrräder) powered the transportation of ore or winnings. Depending on the terrain conditions the reversible wheels were located either in underground wheel houses (Radstuben) near the shaft (the cable drum being set on the same axle as the water wheel) or above ground in the valley. When using the latter method the wheel's rotation was converted into reciprocating motion using a crank mechanism (
Krummen Zapfen) and transmitted over twin flat rods, several hundred metres long, to the shaft. Here, reciprocating motion was re-converted into rotary motion.
Due to the availability of water power this system was used until the closure of the Clausthal and Lautenthal Pits in the 1930s (e.g. at the Silbersegen Shaft and the Black Pit or Schwarze Grube). steam power
was first used in earnest when the stone coal necessary for its operation could be delivered by railway towards the end of the 19th century. Electricity began to be generated at about the same time using water power from the Upper Harz Water Regale
- an extensive network of ponds, dams, ditches and tunnels, originally built to supply the mines with water power. In 1900 water was passed through turbine
s and electrical winding engines
. At that time modern pits emerged with steel hoist frames. The most important innovation in the Upper Harz hauling technology was the Albert Cable (Albert-Seil). Chief Mining Engineer (Oberbergrat) Wilhelm Albert
(1787–1846) made a cable out of steel wire which was first successfully tested on 23 July 1834 at the Carolina Shaft. That was the birth of the wire cable. As the distance between shaft and workings lengthened and increasing quantities of material had to be moved, wheelbarrows or small wagons (the Hunte or Hunde) were used underground as horizontal methods of transportation. Up to 1800 they ran on wooden planks with flange
less wheels and guide pins (Spurnägeln). Thereafter iron rails took over, initially as hand-forged rails (Hammelpfote) only one metre long. Until 1900 the wagons were almost always pushed by hand. Pit ponies were not used in the Upper Harz. From 1905 at the Clausthal Ore Mine (Erzbergwerk Clausthal) underground haulage was carried out using conductor engines in the gallery known as the Tiefsten Wasserstrecke or "Deepest Watercourse". In the Grund Ore Mine (Erzbergwerk Grund) battery-driven locomotives were used from the 1970s and, finally, diesel engines on wheels with rubber tyres. One feature mining in the Upper Harz was the underground transportation of material in boats on the Tiefe Wasserstrecke about 300 metres deep, in Clausthal and Zellerfeld from 1835 to 1898.
Until the beginning of the 19th century the miners of the Upper Harz had to enter and leave the mine using ladders. Towards the end, for shaft depths of around 700 metres this took up to 2 hours of the daily work time. This effort was almost impossible for older miners. In 1833, master miner (Oberbergmeister) Georg Ludwig Wilhelm Dörell (1793–1854) came up with a simple, but ingenious mechanical method of getting in and out of the mine, the man engine
. Following successful pilot trials in the Spiegelthal Hope Shaft (Spiegelthaler Hoffnungsschacht), a light shaft for the Tiefen George Gallery (Tiefen-Georg-Stollen) in Wildemann the first main shaft to be equipped with a man engine was the Duke George William Shaft (Herzog Georg Wilhelm) in the Burgstätter Mining Field. The first man engines had wooden rods with a high dead weight. Due to the water wheel drive and frequent bends in the inclined shafts only a few miners could be transported simultaneously to begin with and they had to periodically switch over to ladders. The use of steel wire cables as rods in the Samson Shaft
at St. Andreasberg and steel man engines with steam or water-column engine drives (Queen Maria Shaft) and Emperor William II Shaft) brought improvements. On the introduction of electrical power around 1900 cable-hauled lifts also became common and remained so until the end. In 1905 passenger trains appeared in the underground galleries for the first time (the so-called Leuteförderwagen or people-transport wagons).
extracted. For example, the density of the Upper Harz lodes was very variable. Unlike the ore at Rammelsberg, the ore minerals were less intermingled with one another and the host rock. This enabled, from the beginning of mining operations in the Upper Harz, ore minerals to be processed into concentrations with a higher metal content than that of unroasted ore
.
In the Middle Ages
until the start of the Early Modern Period
the ore was broken up above ground using sledges and sorted by hand into silver, lead and copper ores and gangue
. The pounding stones (Pochsteine) or stamps
used have occasionally been found in recent times during archaeological excavations. The use of water power increased around the turn of the 16th and 17th centuries and it began to be employed in processing to enrich the ore concentration. On the one hand water was used as an energy source; on the other it was used to wash out the unwanted clay and to separate ore from gangue by making use of the different density
of the minerals. The tailings
from the washing process were simply emptied into the rivers of the Harz along with the used driving water. The low efficiency of the first ore processing machines resulted in a high content of heavy metals in the rivers. As a consequence of using the aforementioned water-based method of processing the stamp mill
s (Pochwerke) were located in the deeper river valleys. As a rule, they obtained water from the pits, where it had been used to drive water wheels and reversing wheels. Until the beginning of the industrial era, mechanical processing was carried out as follows:
The resulting concentrates (Schlieg or Schliech) were sold to the smelters. The preparation of the different types of ore was carried out as far as possible by visually sorting the concentrates by hand in order e.g. to separate out lead from copper concentrates.
After 1850 the small and scattered stamp mills and ore washeries were replaced by central ore dressing plants. The basic steps - coarse crushing - manual separation - sieving - jigging - fine crushing - table work and slime washing - remained much the same. The process was increasingly mechanised and perfected. In 1905 the most modern ore dressing plant in Germany went into operation in Clausthal using the gravity dressing process. It was located near the Ottiliae Shaft on the site of the old central ore processing plant of 1872. It employed up to 650 workers and processed all ore from the Clausthal and Zellerfeld pits until 1930. A change occurred in the 1920s with the introduction of the froth floatation in Bad Grund and later in Lautenthal. This technique enabled the required production of metal concentration without manual pre-sorting and a much higher yield. The flotation process was steadily developed during the 20th century and was used right up to the end of vein mining in the Upper Harz in 1992.
. It is the preparation and smelting of ore that enables metals to be extracted and used. Only by adapting and developing the smelting processes over the course of the centuries could mining in the region be maintained, because the lodes changed their primary metal content sharply with increasing depth.
The beginnings of smelting go back to the start of mining in the Upper Harz in the Early Middle Ages
. In medieval metallurgy, so-called nomadic smelting (Wanderverhüttung) predominated. The smelting sites were only used for a few weeks and followed the logging of the requisite wood. For the charcoal
that was needed for the reduction
of the ore, oak and beech wood were especially well-suited. The billets of wood were located near the smelting sites. The simple, low shaft kilns (Schachtöfen) were built of natural rock and earth from the vicinity. They could only be used for a few days of continuous furnace campaign. Fixed buildings were not erected. Over 200 slag sites and smelting sites have been archaeologically recorded from this smelting period. Since the 1980s the mining archaeology teams of Lothar Klappauf and Friedrich-Albert Linke have carried out excavations and undertaken research.
In the second major phase of mining in the Upper Harz from 1524, smelting was gradually moved into fixed sites. The transportation of logs as rafts and the use of water power led to the selection of advantageous sites on the rivers in the Harz - such as the Innerste
, Grane
and Oker
. At one location that had already been used in medieval times (1180), the Frankenscharrn Hut emerged, which later became the Clausthal Lead Smelting Works (Bleihütte Clausthal), the most famous one in the Upper Harz. It was worked until 31 December 1967. Other important smelters were the silver works (Silberhütte) in Lautenthal
(later merged with the Bleihütte Clausthal), the silver works in Altenau
(to 1911) and the Andreasberg Silver Works (Silberhütte Andreasberg, to 1912). After the Upper Harz metal works were closed the ores of the remaining Grund Ore Mine were reduced in the Upper Harz works (to 1981) and finally in the Binsfeldhammer Lead Works near Aachen. The various metalworks, especially the Clausthal Works left behind considerable environmental damage. By contrast, the buildings and facilities in the Upper Harz have completely disappeared.
From the first mining period until just before the industrial age the so-called precipitation method (Niederschlagsarbeit) was used in the Upper Harz. Instead of the usual roasting (desulphurising) of the ore, the slag was melted using charcoal with granulated iron (Eisengranalien) as a reduction medium using the roast-reaction process (Röst-Reaktions-Verfahren) (direct conversion from metal sulphide to metal) in arched kilns (Krummofen). The comparatively low kiln temperatures of around 1000 °C produced no liquid slag, the residue (gangue) remained in solid form. Not until the development of more powerful fan shaft kilns around 1850 were the concentrates roasted in double-deck ovens (Etagenöfen) and sintering pans and then melted in crucible shaft kilns (Tiegelschaftofen) on silver-containing argentiferous lead (Werkblei) and molten slag. The argentiferous lead was initially worked immediately in the German tests on lightened silver. At the start of the 20th century a multi-stage refining process was carried out in Kesselherden and silver extracted using the Parkes process
.
. Construction wood was needed above ground for accommodation huts as well as mining and smelting buildings. Below ground it was needed for to extend the pits. The greatest consumption of wood, however, was for the smelting of ore with charcoal
. There were some 30,000 wood billets in the Harz alone.
By the Early Middle Ages ore had to be transported over kilometres to the smelting works due to the lack of wood. One particularly well-known route is the transportation road from Goslar's Rammelsberg on the northern edge of the Harz over the Upper Harz to Riefensbeek and Kamschlacken on its southern perimeter. Traces of the road may be seen at many places in the Upper Harz forests.
From the 18th century a systematic reforestation of the largely destroyed forests was begun. As a result, the Upper Harz contributed significantly to the development of modern forestry
. Although not typical of the region, fast-growing spruce
trees were exclusively grown in monoculture
s. The consequences of this intensive forestry, which continued until the 1970s, are still to be seen in many areas of the Upper Harz today.
Because the shortage of wood was time and again one of the limiting factors for mining and smelting, the forestry situation was a standing agenda item at meetings in the mining office.
Upper Harz
The Upper Harz refers to the western and higher part of the Harz mountain range in central Germany. Much of the Upper Harz is over , but at its eastern edge in the High Harz it climbs to over on the Brocken massif.- Geography :...
mining town
Mining town
A mining community, also known as a mining town or a mining camp, is a community that houses miners. Mining communities are usually created around a mine or a quarry for the extraction or smeltering of ore.-United States:...
s of Clausthal, Zellerfeld
Clausthal-Zellerfeld
Clausthal-Zellerfeld is a town in Lower Saxony, Germany. It is located in the southwestern part of the Harz mountains. Its population is approximately 15,000, Clausthal-Zellerfeld is also the seat of the Samtgemeinde Oberharz....
, Sankt Andreasberg
Sankt Andreasberg
Sankt Andreasberg is a town and a former municipality in the district of Goslar, in Lower Saxony, Germany. Since 1 November 2011, it is part of the town Braunlage. It is situated in the Harz, approximately 7 km west of Braunlage proper, and 20 km east of Osterode am Harz.- History :Sankt...
, Wildemann
Wildemann
Wildemann is a town in the district of Goslar, in Lower Saxony, Germany. It is situated in the west of the Harz, northwest of Clausthal-Zellerfeld. It is part of the Samtgemeinde Oberharz....
, Grund
Bad Grund
Bad Grund is a town in the district of Osterode, in Lower Saxony, Germany. It is situated in the western Harz, approx. 7 km west of Clausthal-Zellerfeld, and 10 km north of Osterode am Harz....
, Lautenthal
Lautenthal
The formerly free mining town of Lautenthal is a state-recognised, climatic spa with around 2,000 inhabitants that has been part of the borough of Langelsheim since 1972.- Geography :...
und Altenau
Altenau, Lower Saxony
Altenau is a town in the district of Goslar, in Lower Saxony, Germany.It is situated in the middle of the Harz mountains, between Clausthal-Zellerfeld and the Brocken...
.
History
The Upper Harz was once one of the most important mining regions in Germany. The major products of its mines were silver, copper, lead, iron and, from the 19th century, zinc as well. The main source of income, however, was silver. From the 16th to the middle of the 19th centuries about 40–50 % of the entire German silver production originated in the Upper Harz. The taxes raised from this contributed significantly to the revenue of the royal houses in Hanover and Brunswick-Wolfenbüttel and helped to secure their positions of power and influence within the empire.Its lucrativeness justified a high commitment in terms of investment and effort. The Upper Harz mining industry produced a considerable number of innovations and inventions, including such important advances as the man engine
Man engine
A man engine is a mechanism of reciprocating ladders and stationary platforms installed in mines to assist the miners’ journeys to and from the working levels...
, the water-column engine and the wire cable.
In the Upper Harz, vein mining (Gangerzbergbau) predominated. Excavation followed the almost vertically standing lodes or veins (Erzgängen) downwards. In their heyday the Upper Harz Mines were among the deepest in the world. For example, as early as 1700 or so shafts were already exceeding depths of 300 metres and, around 1830, a depth of 600 metres was achieved – which was considered significant at that time because it was below sea level.
The Middle Ages
Mining activity in the Harz goes back to the 10th and 11th centuries. The first water wheels to supply energy to the mines were constructed in the 13th century in the Pandelbach valley southeast of SeesenSeesen
Seesen is a town and municipality in the district of Goslar, in Lower Saxony, Germany. It is situated on the northwestern edge of the Harz mountain range, approx...
. At that time mining, including this early use of water systems, was carried out by the Cistercian abbey of Walkenried
Walkenried Abbey
Walkenried Abbey was one of the most celebrated Cistercian abbeys of Germany, located in the village of Walkenried in the district of Osterode in Lower Saxony, Germany.-History:...
. At first outcropping lodes on the surface of the ground were sought out and sections of ore near the surface were dug out with hammers and chisels. Mining first boomed between 1200 and 1360. In the upper workings there were particularly rich veins of silver ore (up to 9% Ag).
Plague
Black Death
The Black Death was one of the most devastating pandemics in human history, peaking in Europe between 1348 and 1350. Of several competing theories, the dominant explanation for the Black Death is the plague theory, which attributes the outbreak to the bacterium Yersinia pestis. Thought to have...
epidemics during the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
depopulated the Harz to a great extent and almost brought mining operations to a standstill. Another factor was probably that mining had reached its technical limits at the time with depths of up to about 60 m.
Early Modern Period to the Industrial Revolution
A clear recovery followed from about 1520 onwards, initially at the instigation of the Duke of Brunswick-Wolfenbüttel, Henry the YoungerHenry V, Duke of Brunswick-Lüneburg
Henry , Duke of Brunswick-Lüneburg, called the Younger, was Prince of Wolfenbüttel from 1514 until his death...
. But it was his son, Julius, Duke of Brunswick-Lüneburg
Julius, Duke of Brunswick-Lüneburg
Julius of Brunswick-Lüneburg , Duke of Brunswick-Lüneburg, was prince of Wolfenbüttel from 1568 until his death....
, who gave added impetus to existing mining operations in the Upper Harz and initiated the creation of further infrastructure, especially the structures of the Upper Harz Water Regale
Upper Harz Water Regale
The Upper Harz Water Regale is a system of dams, reservoirs, ditches and other structures, much of which was built from the 16th to 19th centuries to divert and store the water that drove the water wheels of the mines in the Upper Harz region of Germany...
to provide water power for the mines. In order to entice the necessary labourers, tradesmen and even mining companies to the Harz, the dukes granted 'mining freedoms' (Bergfreiheiten) based on Bohemian and Saxon practice.
Because considerable energy was needed to dewater the mines and the consumption for this grew as the mines became deeper and deeper, attempts were made early on to reduce energy consumption by driving drainage adits. This entailed cutting tunnels from the mine into the neighbouring valleys, through which water could drain away downhill under gravity. The deeper the dewatering level lay, the longer these adits needed to be. The longest of these tunnels was the Ernst August Tunnel, built in the mid-19th century, which was 26 kilometres long. It collected water from the mines in Bockswiese, Lautenthal, Zellerfeld, Clausthal and Wildemann and transported it to Gittelde
Gittelde
Gittelde is a municipality in the district of Osterode, in Lower Saxony, Germany....
on the edge of the Harz.
The Upper Harz mines attained their greatest lucrativity in the 16th and 17th centuries, even though there were frequent crises during that time. In 1690 the metal produced reached a quantity that was not exceeded until 1850. That was especially thanks to the construction of artificial water supply structures and the introduction of gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...
for rock blasting
Rock blasting
Rock blasting is the controlled use of explosives to excavate, break down or remove rock. It is practised most often in mining, quarrying and civil engineering such as dam or road construction...
from 1630 onwards. During the course of the 18th century there were constant crises as a result of the lack of wood. The problem was eased by the introduction of coking coal for the smelters around 1800. On 1 January 1864 the mines were nationalised by the Kingdom of Hanover
Kingdom of Hanover
The Kingdom of Hanover was established in October 1814 by the Congress of Vienna, with the restoration of George III to his Hanoverian territories after the Napoleonic era. It succeeded the former Electorate of Brunswick-Lüneburg , and joined with 38 other sovereign states in the German...
.
Industrial Revolution to the Closure of the Mines
Following the annexation of the Kingdom of Hanover by the Kingdom of PrussiaKingdom of Prussia
The Kingdom of Prussia was a German kingdom from 1701 to 1918. Until the defeat of Germany in World War I, it comprised almost two-thirds of the area of the German Empire...
in 1866 the Royal Prussian Mining Inspectorate (Königlich-Preußische Bergbauinspektion) took over the running of mines in the Upper Harz. It was succeeded in 1924 by Preussag
Preussag
Preussag AG was a German mining company which later operated in a variety of industries. It was incorporated on October 9, 1923 as Preußische Bergwerks- und Hütten-Aktiengesellschaft ....
. Around 1900 shaft depths of 1,000 metres were reached and the mining of ore became increasingly costly. At the same time the mines had to compete with other domestic and foreign mines in a climate of ever-improving transportation. Overexploitation during the First World War and plummeting metal prices resulted in major closures at the height of the Great Depression
Great Depression
The Great Depression was a severe worldwide economic depression in the decade preceding World War II. The timing of the Great Depression varied across nations, but in most countries it started in about 1929 and lasted until the late 1930s or early 1940s...
in 1930, when the big mines around Clausthal-Zellerfeld
Clausthal-Zellerfeld
Clausthal-Zellerfeld is a town in Lower Saxony, Germany. It is located in the southwestern part of the Harz mountains. Its population is approximately 15,000, Clausthal-Zellerfeld is also the seat of the Samtgemeinde Oberharz....
, Bockswiese and Lautenthal
Lautenthal
The formerly free mining town of Lautenthal is a state-recognised, climatic spa with around 2,000 inhabitants that has been part of the borough of Langelsheim since 1972.- Geography :...
had to close. Mining operations continued in Bad Grund, however, until 1992.
Re-use for electricity generation
Following the closure of the mines in 1930, several shafts switched to the generation of electricity Here, water from the Upper Harz Water Regale's network of ponds and channels was transported down chutes into the shafts, in which turbinesWater turbine
A water turbine is a rotary engine that takes energy from moving water.Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy...
were driven to produce electricity at the level of the deepest drainage adit. The generation of electricity was carried out by Preussag until 1980 in the Kaiser Wilhelm (maximum output 4.5 MW) and Ottiliae (maximum output 1.5 MW) shafts. The hydropower stations were closed in the early 1980s when the water rights expired and the profitability of the power stations continued to fall at a time of sharply rising wages and stagnating electricity prices. These years saw the permanent closure of the last surviving mines.
Mining the ore
In the early days of mining in the Upper Harz simple open cast working (Schurfe) was the predominant method of miningMining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
. With increasing depth a form of mixed mining developed that was somewhere between open cast and underground mining. These mines were known as glory holes (Pingen) or simply dip mines (Unterwerksbau). The ore deposits that lay immediately on the surface were quickly exhausted and, as early as the 12th and 13th century miners were forced to switch entirely over to underground mining. The mining methods that could be used were limited by the steep, almost vertical, lenticles
Lens (geology)
In geology a lens is a body of ore or rock or a deposit that is thick in the middle and thin at the edges, resembling a convex lens in cross-section. Adjective: "lenticular"....
of ore, which were only a few metres wide, but dipped for several hundred metres into the earth. Hauling shafts were usually positioned in centre of the ore allotment on the lode and followed it into the ground. This resulted in inclined shafts with their characteristic, right-angled, longitudinal sections and frequent changes of angle away from the vertical. There were two reasons for this approach: firstly, it had to be possible to extract ore from the beginning (as soon as the shaft was sunk) in order to make the pit economical as early as possible. Secondly, the rock in the ore lode, which formed a 'zone of disturbance', was much softer than the surrounding rock. The typical Harz grauwacke was far harder than concrete. As a result the majority of drainage adits followed the vein. From the shaft, main gangways, the so-called Feldortstrecken, were driven out to the boundary of the mine allotment. From these gangways, miners began to extract the ore, heading downwards into the floor, by 'brushing down' (Nachreißen) in stepped fashion, a technique known as underhand stoping. The stope
Stoping (mining method)
Stoping is the removal of the wanted ore from an underground mine leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to cave into the stope, although in most cases artificial support is also provided...
s had a height of up to 3 metres and followed one another about 5 to 6 metres apart. In longitudinal section, therefore, a pit looked like a Christmas tree standing on its head. The deepest point of the pit was usually the main shaft. This enabled it to collect pit water in the shaft 'sump'. As mining progressed the shaft was sunk deeper.
The packing (gangue material used for filling) from the upper main gangways was placed in the exhausted cavities (the so-called 'old man' or Alter Mann). This required the erection of a wooden ceiling over the active workings so that packing material did not fall into it and onto the face workers there. If the expected supply of ore or its quality did not justify sinking the main shaft deeper, or if the workings were a long way from it, draw-shafts were sunk. These blind shafts saved having to pack the 'old man'. In the Hornstatt, 1 or 2 labourers (Knechte) worked a hand winch
Winch
A winch is a mechanical device that is used to pull in or let out or otherwise adjust the "tension" of a rope or wire rope . In its simplest form it consists of a spool and attached hand crank. In larger forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and...
and lifted the ore to the next highest main gallery.
From 1633 gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...
was used both for ore extraction and for driving gangways. This increased the daily headway considerably, from a few centimetres into the lode to a metre or more. The disadvantage, however, was that even more wood was needed to extend the mine, because blasting
Rock blasting
Rock blasting is the controlled use of explosives to excavate, break down or remove rock. It is practised most often in mining, quarrying and civil engineering such as dam or road construction...
caused the rock to fissure. When blasting, first a cut in the lode was made about 3 metres high and deep and a little less than a metre wide using hammer and chisel. Next one or two transverse boreholes with a 6–7 cm diameter were drilled by hand Usually two-man boring was employed: one turned the borer whilst a second hit it with his sledge. The holes were filled with gunpowder and stuffed with a wooden peg which had a hole for a slow-match wick. Unlike blasting with modern explosive, the stemming had to be wedged in using an iron rod centred on the borehole and a thick wooden prop in a slot (Bühnloch) on the opposite side. This operation frequently led to serious accidents when the gunpowder self-ignited as a result of friction-generated heat. Normal detonation was carried out using cord that had been impregnated with sulphur and gunpowder.
After clearing the blast debris, the material to be screened was loaded into wagons (Hunde or Hunte) using rakes (Kratze) and tubs (Trog). Larger boulders (Wände) were first broken up with sledges and crowbars.
From the second half of the 18th century the method of mining was reversed. Now the roof was always mined and so extraction proceeded upwards. That meant the miners worked on top of the packing and could transport the ore under gravity using so-called chute holes (Rollöcher or Rollen) rather than shafts. Overhand stoping remained the only mining method in the Upper Harz mines until the end and was perfected in the final years through the use of trackless wagons, roof bolts
(Ankern), shotcrete
Shotcrete
Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....
and lean concrete
Properties of concrete
Concrete has relatively high compressive strength, but significantly lower tensile strength, and as such is usually reinforced with materials that are strong in tension . The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix...
packing. Trials with sublevel stoping (Teilsohlenbruchbau) and square set timbering (Blockbau mit Rahmenzimmerung) did not get past the experimental stage.
In the middle of the 19th century, the many individual pits transferred to larger mine complexes with central shafts, at which point the sinking of inclined shafts and the mixing of layout and equipment with the workings was abandoned entirely. The central, vertical shafts lay in the host rock (usually in the hanging wall), just as permanently established as the main gangways (usually in the footwall).
Extraction technology
To begin with the ore was chiselled free and carted to the surface of the open pits or shallow mines in baskets. Once shaft depths increased to between about 10–60 metres hand winches (Handhäspel) were used, operated by one or two workers (Knechten). The crude ore was placed in wooden buckets for transportation. For the rather short, horizontal gangways leading to the shaft the ore was carried in Trogs for several centuries (long before the introduction of blasting). In the 17th century the shafts reached depths of between 100 and 200 m. Ore could no longer be removed by hand and horsepower was increasingly used. The horses worked in a cone-shaped building, the Göpel or Gaipel, which housed a horse whimWhim (mining)
A whim, also called a whim gin or a horse capstan, is a device similar to a windlass used in mining for hauling materials to the surface. It comprises a capstan or a wide drum with a vertical axle. A rope is wound around the drum, with both ends traversing several pulleys and hanging down the mine...
, a winch that was driven by the horses walking in a circle. The hauling cable (made of natural fibre) or cast-iron chain was wound up and down over a vertical axle. The cable was routed down the shaft and hauled barrels of ore up and down. Due to the shaft's incline, barrels were covered with iron runners on one side, resting partly on the side of the shaft. Above ground at the pithead the ore was emptied out and transported away by horse and cart for processing. From the 18th century shaft depths of several hundred metres were being achieved and horse whims were reaching the limits of their capability. Where the mines were lucrative and their energy consumption high as a result of shaft depth or the ingress of water, water power had been used since the 16th century. Water wheel
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...
s (Kunsträder) drove piston pump
Piston pump
A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases.-Types:* Axial piston pump* Radial piston pump...
s in order to keep the mine dewatered (zu Sumpfe). Reversible water wheels (Kehrräder) powered the transportation of ore or winnings. Depending on the terrain conditions the reversible wheels were located either in underground wheel houses (Radstuben) near the shaft (the cable drum being set on the same axle as the water wheel) or above ground in the valley. When using the latter method the wheel's rotation was converted into reciprocating motion using a crank mechanism (
Krummen Zapfen) and transmitted over twin flat rods, several hundred metres long, to the shaft. Here, reciprocating motion was re-converted into rotary motion.
Due to the availability of water power this system was used until the closure of the Clausthal and Lautenthal Pits in the 1930s (e.g. at the Silbersegen Shaft and the Black Pit or Schwarze Grube). steam power
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...
was first used in earnest when the stone coal necessary for its operation could be delivered by railway towards the end of the 19th century. Electricity began to be generated at about the same time using water power from the Upper Harz Water Regale
Upper Harz Water Regale
The Upper Harz Water Regale is a system of dams, reservoirs, ditches and other structures, much of which was built from the 16th to 19th centuries to divert and store the water that drove the water wheels of the mines in the Upper Harz region of Germany...
- an extensive network of ponds, dams, ditches and tunnels, originally built to supply the mines with water power. In 1900 water was passed through turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
s and electrical winding engines
Winding engine
A winding engine is a stationary engine used to control a cable, for example to power a mining hoist at a pit head. Electric hoist controllers have replaced proper winding engines in modern mining, but use electric motors that are also traditionally referred to as winding engines.Most proper...
. At that time modern pits emerged with steel hoist frames. The most important innovation in the Upper Harz hauling technology was the Albert Cable (Albert-Seil). Chief Mining Engineer (Oberbergrat) Wilhelm Albert
Wilhelm Albert
Wilhelm August Julius Albert was a German mining administrator, best remembered as the first person to record observations of metal fatigue....
(1787–1846) made a cable out of steel wire which was first successfully tested on 23 July 1834 at the Carolina Shaft. That was the birth of the wire cable. As the distance between shaft and workings lengthened and increasing quantities of material had to be moved, wheelbarrows or small wagons (the Hunte or Hunde) were used underground as horizontal methods of transportation. Up to 1800 they ran on wooden planks with flange
Flange
A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel...
less wheels and guide pins (Spurnägeln). Thereafter iron rails took over, initially as hand-forged rails (Hammelpfote) only one metre long. Until 1900 the wagons were almost always pushed by hand. Pit ponies were not used in the Upper Harz. From 1905 at the Clausthal Ore Mine (Erzbergwerk Clausthal) underground haulage was carried out using conductor engines in the gallery known as the Tiefsten Wasserstrecke or "Deepest Watercourse". In the Grund Ore Mine (Erzbergwerk Grund) battery-driven locomotives were used from the 1970s and, finally, diesel engines on wheels with rubber tyres. One feature mining in the Upper Harz was the underground transportation of material in boats on the Tiefe Wasserstrecke about 300 metres deep, in Clausthal and Zellerfeld from 1835 to 1898.
Movement
Man engine
A man engine is a mechanism of reciprocating ladders and stationary platforms installed in mines to assist the miners’ journeys to and from the working levels...
. Following successful pilot trials in the Spiegelthal Hope Shaft (Spiegelthaler Hoffnungsschacht), a light shaft for the Tiefen George Gallery (Tiefen-Georg-Stollen) in Wildemann the first main shaft to be equipped with a man engine was the Duke George William Shaft (Herzog Georg Wilhelm) in the Burgstätter Mining Field. The first man engines had wooden rods with a high dead weight. Due to the water wheel drive and frequent bends in the inclined shafts only a few miners could be transported simultaneously to begin with and they had to periodically switch over to ladders. The use of steel wire cables as rods in the Samson Shaft
Samson Pit
The Samson Pit or Samson Mine is an historic silver mine in Sankt Andreasberg in the Upper Harz region of central Germany.The pit has one of the oldest man engines in the world still working and it can be seen in operation during guided tours. The man engine, installed in the Samson Pit in 1837,...
at St. Andreasberg and steel man engines with steam or water-column engine drives (Queen Maria Shaft) and Emperor William II Shaft) brought improvements. On the introduction of electrical power around 1900 cable-hauled lifts also became common and remained so until the end. In 1905 passenger trains appeared in the underground galleries for the first time (the so-called Leuteförderwagen or people-transport wagons).
Preparation of Upper Harz ore
The processing of minerals in the Upper Harz depended on the type of oreOre
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
extracted. For example, the density of the Upper Harz lodes was very variable. Unlike the ore at Rammelsberg, the ore minerals were less intermingled with one another and the host rock. This enabled, from the beginning of mining operations in the Upper Harz, ore minerals to be processed into concentrations with a higher metal content than that of unroasted ore
Roasting (metallurgy)
Roasting is a step in the processing of certain ores. More specifically, roasting is a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component. Often before roasting, the ore has already been partially purified, e.g. by froth...
.
In the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
until the start of the Early Modern Period
Early modern period
In history, the early modern period of modern history follows the late Middle Ages. Although the chronological limits of the period are open to debate, the timeframe spans the period after the late portion of the Middle Ages through the beginning of the Age of Revolutions...
the ore was broken up above ground using sledges and sorted by hand into silver, lead and copper ores and gangue
Gangue
In mining, gangue is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. The separation of mineral from gangue is known as mineral processing, mineral dressing or ore dressing and it is a necessary and often significant aspect of mining...
. The pounding stones (Pochsteine) or stamps
Stamp mill
A stamp mill is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation....
used have occasionally been found in recent times during archaeological excavations. The use of water power increased around the turn of the 16th and 17th centuries and it began to be employed in processing to enrich the ore concentration. On the one hand water was used as an energy source; on the other it was used to wash out the unwanted clay and to separate ore from gangue by making use of the different density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
of the minerals. The tailings
Tailings
Tailings, also called mine dumps, slimes, tails, leach residue, or slickens, are the materials left over after the process of separating the valuable fraction from the uneconomic fraction of an ore...
from the washing process were simply emptied into the rivers of the Harz along with the used driving water. The low efficiency of the first ore processing machines resulted in a high content of heavy metals in the rivers. As a consequence of using the aforementioned water-based method of processing the stamp mill
Stamp mill
A stamp mill is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation....
s (Pochwerke) were located in the deeper river valleys. As a rule, they obtained water from the pits, where it had been used to drive water wheels and reversing wheels. Until the beginning of the industrial era, mechanical processing was carried out as follows:
- Coarse crushing with a heavy sledge (later with crushing machinesCrusherA crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials , so that pieces...
).
- Wet screening in coarse sieves (trommelTrommelA trommel is a screened cylinder used to separate materials by size - for example, separating the biodegradable fraction of mixed municipal waste or separating different sizes of crushed stone....
s). The ore is washed (and gangue removed) and sorted by size.
- Manual separation (Handscheidung) of the coarse lumps of ore, pure ore minerals (so-called rough ores or Derberze) were sorted, dry crushed and went straight on sale (to the smelters). The work on the picking tables (Klaustischen) was carried out mainly by women, the elderly and youths.
- Washing (Siebwaschen) of the 'smalls' (Grubenkleins) or ore dust (Feinerze) in water-filled jigging tubs (Setzfässern). By dipping an ore-filled sieve several times in water the heavier pieces that were more ore-rich, settled in a lower layer. This process was later mechanised using jigging sieves (Setzmaschinen, not to be confused with the Setzmaschinen used in crushing).
- Wet stampingStamp millA stamp mill is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation....
(Nasspochen) of ore which is more finely mixed with the gangue until it forms a 'sand'.
- Separation of the stamped ore on tables (Herdwäschen) using gravity. Depending on the design and drive mechanism, they were called vanners (Planherde), percussion tables (Stoßherde) or rotating tables (Rundherde). The fundamental principle was that heavy particles of ore remained on the table and the gangue would be washed away by water.
- The slimes or tailings from the preceding set of processes were further separated from the particles of ore in tyes (Schlammgräben) by sedimentation.
The resulting concentrates (Schlieg or Schliech) were sold to the smelters. The preparation of the different types of ore was carried out as far as possible by visually sorting the concentrates by hand in order e.g. to separate out lead from copper concentrates.
After 1850 the small and scattered stamp mills and ore washeries were replaced by central ore dressing plants. The basic steps - coarse crushing - manual separation - sieving - jigging - fine crushing - table work and slime washing - remained much the same. The process was increasingly mechanised and perfected. In 1905 the most modern ore dressing plant in Germany went into operation in Clausthal using the gravity dressing process. It was located near the Ottiliae Shaft on the site of the old central ore processing plant of 1872. It employed up to 650 workers and processed all ore from the Clausthal and Zellerfeld pits until 1930. A change occurred in the 1920s with the introduction of the froth floatation in Bad Grund and later in Lautenthal. This technique enabled the required production of metal concentration without manual pre-sorting and a much higher yield. The flotation process was steadily developed during the 20th century and was used right up to the end of vein mining in the Upper Harz in 1992.
Smelting in the Upper Harz
Mining in the Upper Harz is inextricably bound up with metallurgyMetallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...
. It is the preparation and smelting of ore that enables metals to be extracted and used. Only by adapting and developing the smelting processes over the course of the centuries could mining in the region be maintained, because the lodes changed their primary metal content sharply with increasing depth.
The beginnings of smelting go back to the start of mining in the Upper Harz in the Early Middle Ages
Early Middle Ages
The Early Middle Ages was the period of European history lasting from the 5th century to approximately 1000. The Early Middle Ages followed the decline of the Western Roman Empire and preceded the High Middle Ages...
. In medieval metallurgy, so-called nomadic smelting (Wanderverhüttung) predominated. The smelting sites were only used for a few weeks and followed the logging of the requisite wood. For the charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
that was needed for the reduction
Reduction
Reduction, reduced, or reduce may refer to:- Chemistry :* Reduction, part of a reduction-oxidation reaction where oxygen is being removed from a compound.** Reduced gas, a gas with a low oxidation number...
of the ore, oak and beech wood were especially well-suited. The billets of wood were located near the smelting sites. The simple, low shaft kilns (Schachtöfen) were built of natural rock and earth from the vicinity. They could only be used for a few days of continuous furnace campaign. Fixed buildings were not erected. Over 200 slag sites and smelting sites have been archaeologically recorded from this smelting period. Since the 1980s the mining archaeology teams of Lothar Klappauf and Friedrich-Albert Linke have carried out excavations and undertaken research.
In the second major phase of mining in the Upper Harz from 1524, smelting was gradually moved into fixed sites. The transportation of logs as rafts and the use of water power led to the selection of advantageous sites on the rivers in the Harz - such as the Innerste
Innerste
The Innerste is a river in Lower Saxony, Germany. It is a right tributary of the Leine river and 95 km in length.- Origin of the name :...
, Grane
Grane (river)
The Grane is a right tributary of the Innerste river near Goslar.It rises in the vicinity of Hahnenklee in the Upper Harz and discharges about 12 km later into the Innerste near Langelsheim . At Herzog Juliushütte, in the municipality of Astfeld near Goslar, it is controlled by the Grane Dam....
and Oker
Oker
The Oker is a river in Lower Saxony, Germany, that has historically formed an important political boundary. It is a left tributary of the River Aller, in length and runs in a generally northerly direction.- Course :...
. At one location that had already been used in medieval times (1180), the Frankenscharrn Hut emerged, which later became the Clausthal Lead Smelting Works (Bleihütte Clausthal), the most famous one in the Upper Harz. It was worked until 31 December 1967. Other important smelters were the silver works (Silberhütte) in Lautenthal
Lautenthal
The formerly free mining town of Lautenthal is a state-recognised, climatic spa with around 2,000 inhabitants that has been part of the borough of Langelsheim since 1972.- Geography :...
(later merged with the Bleihütte Clausthal), the silver works in Altenau
Altenau, Lower Saxony
Altenau is a town in the district of Goslar, in Lower Saxony, Germany.It is situated in the middle of the Harz mountains, between Clausthal-Zellerfeld and the Brocken...
(to 1911) and the Andreasberg Silver Works (Silberhütte Andreasberg, to 1912). After the Upper Harz metal works were closed the ores of the remaining Grund Ore Mine were reduced in the Upper Harz works (to 1981) and finally in the Binsfeldhammer Lead Works near Aachen. The various metalworks, especially the Clausthal Works left behind considerable environmental damage. By contrast, the buildings and facilities in the Upper Harz have completely disappeared.
From the first mining period until just before the industrial age the so-called precipitation method (Niederschlagsarbeit) was used in the Upper Harz. Instead of the usual roasting (desulphurising) of the ore, the slag was melted using charcoal with granulated iron (Eisengranalien) as a reduction medium using the roast-reaction process (Röst-Reaktions-Verfahren) (direct conversion from metal sulphide to metal) in arched kilns (Krummofen). The comparatively low kiln temperatures of around 1000 °C produced no liquid slag, the residue (gangue) remained in solid form. Not until the development of more powerful fan shaft kilns around 1850 were the concentrates roasted in double-deck ovens (Etagenöfen) and sintering pans and then melted in crucible shaft kilns (Tiegelschaftofen) on silver-containing argentiferous lead (Werkblei) and molten slag. The argentiferous lead was initially worked immediately in the German tests on lightened silver. At the start of the 20th century a multi-stage refining process was carried out in Kesselherden and silver extracted using the Parkes process
Parkes process
The Parkes process is a pyrometallurgical industrial process for removing silver from lead, during the production of bullion. It is an example of liquid-liquid extraction....
.
Mining and forestry
The steadily rising demand for wood from the pits and smelting works led to overexploitation of the forests by the Early Middle AgesEarly Middle Ages
The Early Middle Ages was the period of European history lasting from the 5th century to approximately 1000. The Early Middle Ages followed the decline of the Western Roman Empire and preceded the High Middle Ages...
. Construction wood was needed above ground for accommodation huts as well as mining and smelting buildings. Below ground it was needed for to extend the pits. The greatest consumption of wood, however, was for the smelting of ore with charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
. There were some 30,000 wood billets in the Harz alone.
By the Early Middle Ages ore had to be transported over kilometres to the smelting works due to the lack of wood. One particularly well-known route is the transportation road from Goslar's Rammelsberg on the northern edge of the Harz over the Upper Harz to Riefensbeek and Kamschlacken on its southern perimeter. Traces of the road may be seen at many places in the Upper Harz forests.
From the 18th century a systematic reforestation of the largely destroyed forests was begun. As a result, the Upper Harz contributed significantly to the development of modern forestry
Forestry
Forestry is the interdisciplinary profession embracing the science, art, and craft of creating, managing, using, and conserving forests and associated resources in a sustainable manner to meet desired goals, needs, and values for human benefit. Forestry is practiced in plantations and natural stands...
. Although not typical of the region, fast-growing spruce
Spruce
A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
trees were exclusively grown in monoculture
Monoculture
Monoculture is the agricultural practice of producing or growing one single crop over a wide area. It is also known as a way of farming practice of growing large stands of a single species. It is widely used in modern industrial agriculture and its implementation has allowed for large harvests from...
s. The consequences of this intensive forestry, which continued until the 1970s, are still to be seen in many areas of the Upper Harz today.
Because the shortage of wood was time and again one of the limiting factors for mining and smelting, the forestry situation was a standing agenda item at meetings in the mining office.
See also
- List of mines in the Harz
- Mining and metallurgy in medieval EuropeMining and metallurgy in medieval EuropeThe Middle Ages in Europe cover the time span from the 5th c. AD, marked by the decay of the Roman Empire, to the 16th c. AD, when social and economic factors shifted Europe towards the Modern Era. During the millennium between classical antiquity and the modern period, a series of technological...
- Mining in the Lower Harz
- Upper Harz Mining MuseumUpper Harz Mining MuseumThe Upper Harz Mining Museum is a museum of technological and cultural history in Clausthal-Zellerfeld in the Harz mountains of central Germany...
- Roter Bär PitRoter Bär PitThe Roter Bär Pit in Sankt Andreasberg in the Upper Harz is an iron ore mine that was worked from about 1800 until the 1860s. Today it is operated as a show mine under the name of Roter Bär Pit Educational Mine by the Sankt Andreasberg Society for History and Archaeology...
- Samson PitSamson PitThe Samson Pit or Samson Mine is an historic silver mine in Sankt Andreasberg in the Upper Harz region of central Germany.The pit has one of the oldest man engines in the world still working and it can be seen in operation during guided tours. The man engine, installed in the Samson Pit in 1837,...
- KunstgrabenKunstgrabenA Kunstgraben is a type of man-made water channel that was once used by mines to drive the water wheels needed for power, mine drainage and a host of other purposes...
- KunstteichKunstteichA Kunstteich is an historic German term for a man-made lake or pond associated with the mining industry and its technology. These ponds were created by the construction of barriers, typically dams and embankments, and were used to supply hydropower and water to the mines. Water stored in the...