Prospectors
A prospectors or miners is a prospector who primarily or exclusively with the gold dealing seeking. In contrast to modern industrial mining, the gold prospector, also known as gold washer or gold digger , traditionally also exploits the deposit that has been found . The methods differ depending on the type of deposit and the financial resources of the prospector. Although the search for gold has always been pursued for economic reasons and still is today, it has become a popular leisure activity in various industrialized nations.
history
Since ancient times, gold has mainly been extracted from soap deposits worldwide . The site map of an Egyptian gold mine is already recorded on the Turin papyrus , and the search for gold was also reflected in the Greek Argonauts legend . The Bible mentions the gold lands of Hawila and Ophir . The Romans had gold-bearing rocks mined on a large scale by slaves, among other things by bringing large amounts of water through aqueducts and canals and flushing them through . The best-known example of this are the first-century Las Médulas gold mines in northern Spain.
In the 14./15. In the 19th century, the Rauris Goldberg in the Hohe Tauern was the largest gold mining area in Europe. 10% of global gold production was mined by up to 3,000 miners . However, large quantities of gold were also imported from Africa at that time, and the idea that the “solar metal” gold was to be found particularly in hot, tropical gold countries, subsequently represented an important impetus for European voyages of discovery overseas. The first highlights were the discovery of gold soaps by Chocó in 1550, and by Minas Gerais in 1693.
The gold rush , as it was immortalized in novels and films, is a modern phenomenon, as it requires a large amount of free labor (the ancient slave laborers were not free, the medieval and early modern miners partly still tied to feudal structures), and sufficient means of transport. A number of famous gold rushes occurred in North America, Australia and South Africa, particularly in the 19th century.
By the General Mining Act of 1872 in America the right to a claim , engl. Gold placer claim by staking out public ground with stakes and nameplate, engl. Claim staking set. Previously, taking possession of prospecting sites was mostly a legal vacuum where the law of the thumb prevailed.
In the 20th century, the production of gold from vein and other deposits in the rock began to exceed that from soap deposits. This was accompanied by a clear division of labor between the prospector (search and find) and the miner (mine). Nevertheless, many people still work as gold prospectors today. Particularly in the so-called developing and emerging countries, gold seekers work in more or less legal mining , sometimes under catastrophic conditions and sometimes with drastic effects on the environment, such as B. the Garimpeiros in Brazil, the Pirquineros in Chile or the Gambusinos in Mexico.
Soap deposits
In the case of gold-containing soap deposits, a distinction is made between gold soaps and river soaps. The gold soaps are created where the gold-bearing parent rock has weathered and the gold can be mined in open-cast mines or in tunnels.
River soaps are created in or behind the inside of a curve in a river or stream bed. These river soaps can silt up when the river meanders. The gold remains there together with other heavy minerals , rocks and whole stone blocks because the flow of the water behind the curve decreases or a slight countercurrent forms. Albert Einstein recognized and published the exact principle in 1926 based on the phenomenon that tea leaves collect in the middle when the tea is stirred against the centrifugal force , as a "friction-related secondary circulation" by slowing down the flow at the edge of the river bed (the problem is also known as " Schrödinger's tea leaves ” , the effect also influences the Ekman transport ). According to another theory, with small particles, due to their higher specific surface area, the force of the flow on the particles is greater than the centrifugal force, see also Hydrocyclone # Functionality .
These gold deposits are mostly developed in open-cast mining or by creating stretches within fossil, long-silted river beds (“dead arms”), which are often particularly gold-bearing. The more solidified sediments can be flushed out with pressurized water, excavated with gold dredgers or extracted with mining equipment.
Gold washer
With the safety trough
Panning for gold in a safety trough , also known colloquially as a "gold pan", is one of the oldest and simplest methods of extracting gold particles from unconsolidated river sediments. It is still used today by large mining companies to find new gold deposits. For gold seekers with limited financial means, it may still be the only viable method of gold mining.
Here (pre-screened) fine material from the bottom of a flowing body of water is filled with some water in a mostly round "pan". This mixture is set in a slight, even rotating motion and occasionally shaken (or swung sideways under water). The materials in the pan are sorted according to their density . The denser particles collect on the bottom, the less dense at the edge. By slightly tilting the safety trough, some water with the upper layer of sediment (mud, sand, gravel, etc.) can flow over the edge. If the process is repeated several times, the remaining material with its heavy components (gold, but also platinum and heavy minerals, etc.) is concentrated on the ground.
The method can also be carried out without water; this requires numerous smaller pushes on the side of the pan to enable separation due to the density. Gold was searched for in arid areas, for example in Death Valley .
Since most of the gold soap deposits worldwide are largely exhausted, washing in the safety trough is hardly economical anymore. Usually only fine gold dust is obtained. For the prospecting geologist , however, this can still be a valuable indication of the existence of gold deposits in the rock somewhere further upstream, for the hobby gold prospector a souvenir. Finds of nuggets or gold dust in large quantities are rare today.
However, if a lucrative soap deposit was discovered, the gold prospectors mostly went over to processing larger quantities of sediment in mechanical systems such as washing troughs.
With the wash trough
This technique is the main technique of gold mining. It goes back to simple procedures in which sheepskins were placed in a gold-bearing river. The gold dust then settled between his hair (this is probably the basis of the myth of the golden fleece ). Chinese gold prospectors still used woven woolen cloths for this purpose in the 19th century, which they then burned to melt the gold out.
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A wash trough works on the same principle of density separation as the safety trough, only on a larger scale. The wash trough is a flow channel in which the concentration takes place due to the difference in buoyancy between sand (density: 2.5 g / cm³), heavy minerals (density 3 to 6 g / cm³) and gold (density 19.3 g / cm³). The channels are between 0.5 and 200 m long and 0.1 to 5 m wide. The technical processes are quite complex and partly still not understood, since the flow conditions in a washing trough can be very different. The concentration process is based primarily on the different behavior of materials of different densities in a stratified, laminar flow. In areas with low currents, the materials transported in the channel are deposited and displace one another, depending on their density. The technical implementation, on the other hand, is very simple: flat obstacles ( corrugations ) are inserted into a U-shaped flow channel across the flow direction , behind which the heavy components can be deposited.
Rinse with pressurized water
Environmental activists consider the dismantling of soap deposits with pressurized water to be harmful to the environment because of the large amounts of silt that are flushed into previously clear waters. In fact, between 1853 and 1884, the mining of soap deposits with pressurized water washed away enormous amounts of sediment from the gold fields in California; these were shipped downstream and raised the floor of the Californian long valley in some places by over two meters. Sandbanks up to seven meters wide also formed in San Francisco Bay . This process sparked a countermovement that called itself the Anti-Debris Association . As a result, in January 1884, the washing of debris into the rivers was forbidden by law.
This is why most of the gold mines in soap deposits now have settling basins in which the sediments can settle. At the same time, this ensures that there is always enough water available for the washing troughs. In modern gold mines it is common for the service water to be constantly recycled . When gold prices are high , it is often more economical to recondition old spoil heaps instead of extracting new material.
Pre-sorting
The “cradle” (or “rocking chair”) works in a similar way to the washing trough, in which the material is pre-sorted with a sieve while the apparatus is rocked like a cradle .
Large quantities are pre-sorted mainly with drums. A slightly inclined rotating steel pipe with a sieve on its outlet is called a drum . Inside the cylinder there are lifting bars, sometimes in the form of riveted angle irons. The gold-containing material is introduced at the raised end of the drum. With the addition of water, often under pressure, the material is mechanically loosened and crushed, rinsed through the sieve and separated from the coarsest components. The processed and enriched material can then be further concentrated in smaller systems, such as washing troughs, while the coarse components that do not pass through the sieve are taken to a waste dump.
Gold digger
Soaps hidden at greater depths are searched for and sampled using trenches or boreholes. Geophysical methods such as seismics , gravimetry or geomagnetics can be used to determine the location of underground river beds.
In the rock
When looking for gold deposits in the rock , such as B. gold quartz veins , a variety of methods are used. In the simplest case, the prospector examines the rock during an outcrop ( eroded by wind and water or exposed by demolition) with the naked eye for an outcrop (exposed ore), for signs of hydrothermally changed minerals or for rock types that are gold-bearing or with Gold are known to be socialized. A geologist's hammer , a detailed magnifying glass , a map to mark the place of discovery and a field book for documentation can be completely sufficient as equipment.
On the other hand, the mineralogical and geological properties of gold deposits in solid rock are much more complex than those in soaps. Different prospecting methods are therefore suitable for different types of deposits . The investigation options also depend on the prospect's financial capabilities. Test drillings are often carried out to investigate the subsurface, but indirect geophysical methods can also uncover anomalies . Rock or soil samples can be sent to specialized laboratories for geochemical analysis to determine their gold grade and other geochemical properties. If the number of samples is sufficient, statistical methods can even be used to interpret the results.
Even if the vast majority of global gold production today comes from deep mines and large opencast mines, small-scale gold mining is still widespread, especially in the informal sector and day labor in developing countries .
Concentration and its effects on the environment
Gold particles found were extracted with mercury in the amalgam process by grinding or tumbling (grinding in drums driven by water wheels) , concentrated and freed from dead rock. By heating the dust obtained, the mercury is evaporated and molten gold remains.
This process leads to a significant environmental impact. Unbound mercury contaminates the water, the mercury vapors the air and resublimates from it on the vegetation . Mercury poisoning of the organisms living on the river, including gold washers, is the result.
Because simple gold miners and washers do not recover the mercury by distillation , the amalgam is heated in open vessels with the help of blowtorches. The mercury (boiling point 357 ° C) evaporates into the ambient air and condenses in the environment on cold nights, which leads to mercury contamination of these areas, the rivers and the people living there. It has been estimated that 20 to 30 percent of the gold mined worldwide is obtained by non-industrial prospecting, i.e. by gold prospectors.
In the amalgam process, which was already used in antiquity, the mercury acts as a solvent and an alloy is created from gold and any solid silver that may be present . Gold amalgam is silver in color; Depending on how much mercury is in excess , it is liquid to pasty, doughy and the melting point of the alloy is lower, in the melting range between the melting temperature of gold C (1,064.18 ° C) and mercury (-38.83 ° C).
After the mercury has been rubbed into the rock flour, amalgam and mercury collect at the bottom of the vessel because of their high density; the mercury is allowed to drain off. By heating the amalgam (as described in detail for fire gold plating), the mercury evaporates and what remains is compact raw gold. The remaining rock flour contains traces of mercury; in the overburden from gold mines, accompanying substances such as lead , cadmium , copper and arsenic are mostly found. According to a report of the series New York Times estimated the US Environmental Protection Agency in 2009 that cleaning around American Golderzminen in Nevada would cost to 54 billion US dollars.
A much more environmentally friendly process is gold extraction and purification using the borax process, which can also be accomplished with simple tools. If all gold miners in the world were to use this process, the emission of around 1,000 tons of mercury, about 30% of global mercury emissions, could be avoided.
Gold prospecting as a leisure activity
In different countries of the world the search for gold is practiced today as an outdoor activity and hobby, often on the scenes of a historical gold rush , such as in the United States (especially in the western states), Canada ( Yukon area ), South Africa , Australia and New Zealand (region of Otago ), but also in the touristy mountain regions of Europe, as in Germany , Sweden Småland Ädelfors of Switzerland and Austria ( Rauristal , Hohe Tauern ) or the UK ( Gwynedd in Wales). Usually courses are offered in which interested parties can learn to panning for gold in the safety trough. Hobby gold seekers with metal detectors , on the other hand, are mostly loners looking for nuggets.
Gold panning is also a popular hobby in Germany. The daily yield is between 0.1 and 3 g per person. Nuggets are very rarely found here, almost never larger than 10 g.
Gold discovery sites
Where gold has been mined, leaching is usually found in the waters.
Gold was also found in Germany, for example:
- in the Harz
- in the Thuringian Forest
- in the Rhenish Slate Mountains
- in the Upper Palatinate
- in the Ore Mountains
- in the southern Black Forest
- in the Bavarian Forest
as well as in the places
There are historical sites in Austria
- in the Zillertal ,
- in the Goldberg group of the Hohe Tauern in the Rauris Valley and on the Silberpfennig
- in the Angertal (a side valley of the Gastein Valley near Bad Hofgastein im Pongau ), Land Salzburg and the subsequent smelting in Lend (Salzburg)
- in Pusterwald ( Wölzer Tauern )
- in Oberzeiring near Pusterwald
- In 2013, test bores were made in the disused 14th century Friedrichsstollen in the Rotgüldental near Muhr in Lungau ( Land Salzburg ).
- In the Siflitzgraben municipality of Sachsenburg , Carinthia.
- in Lower Austria in Annaberg , in Grenzleiten near Gloggnitz , Trattenbach and Granigberg in Ottertal , on Erzberg near Edlach , in Gaming and Gösling ( Gösting ) on Eisenstrasse , on Schwarzen Berg and Schlegel Berg west of Türnitz , on Hocheck and Gamaienkogel south of Annaberg
Little gold was found in Switzerland
- around Disentis and Sedrun ( Lukmanierschlucht ),
- in the Malcantone ,
- on the Simplon
- in Lower Valais
In Italy in the Monte Rosa region
- Gold washing
Gold washing used to be carried out on the Elbe and the Weißeritz .
In Germany, so-called river gold ducats were minted from the gold of the rivers Danube , Rhine , Eder , Isar , Inn and Schwarza . They usually show the origin of the gold through pictures and writing. The gold panning for ducats was operated from the 17th to 19th centuries.
On numerous rivers all over Austria (Danube, Inn, Salzach , Große Mühl , Enns , Krems , Kamp (river) etc.) gold was painstakingly panned from secondary deposits ( soap gold ) from the rivers. In 1924, more than 40 kilograms of gold were allegedly mined in Austria.
"Gold panning as an independent line of business hopeless. From Passau-Eferding no gold, then gold also in the tributaries, mostly Ens, in some places with 2 guilders expenses for 2 ducats, but only in the lowlands to Steyr, is only in the coarse sand, the gold-bearing sand layers are very scattered and little powerful, only recommended as a sideline. "
Locations for river gold in Switzerland:
- the Napf area with its rivers, including the Emme and Wigger
- Aare and Reuss
- the Geneva area
- the Alpine Rhine region
as in:
- Napf area with the courses of the fountains , Luthern
- the Geneva area with the rivers Rhone , Arve and Allondon
- as well as the Alpine Rhine area with the Hinterrhein and Rhine to Maienfeld
- in the entire catchment area of the Alpine Rhine above Lake Constance , in the Upper Rhine between Neuhausen am Rheinfall and the mouth of the Aare
- in rivers in eastern Switzerland from deposits of the Rhine glacier
- in the Freiburg ( Broye , Saane and Sense ) and Ticino rivers ( Magliasina , Vedeggio , Breggia ).
Hydraulic engineering systems such as reservoirs and river structures , however, reduce the continuous supply of gold-bearing rubble from the mountains.
Earlier gold panning and gold mining is known in Slovakia in Banská Bystrica , Kremnica and Banská Štiavnica and in numerous other places in Europe.
- possible sites
Numerous field names indicate where gold was washed and found: Goldgrund , Goldgrube (mountain) , Goldscheuer , Goldbrunnen near Alpirsbach (formerly gold mine), also known as “Grein” (from grin = semolina, sand, gravel; from this originated often wrongly green, as in the field name Laundry Green in Oberhausen) or Goldgrien. Whereby gold-like deposits of feline gold also led to gold in field names: Am Goldberg near Oberried, Goldbach, Goldhöfe and Goldmatten near Bernau-Hof . In Switzerland, however, “gold” in a field name can also be traced back to “Göl” for “coarse stone rubble”, but not where gold was mined, where there are “gold holes” ( Meltingen , Bärschwil )
Gold prospectors in literature and film
- Call of the Wild (1903), Wolf's Blood (1906), Call of the Gold (1910) by Jack London .
- Gold Rush (1925) silent film comedy directed by Charlie Chaplin .
- The Treasure of the Sierra Madre (1948) Feature film by John Huston , based on the novel by B. Traven (1927).
- Gold Rush in Alaska American documentary soap
- Benno Kroll (photos), René Burri: Garimpeiro. In: Geo-Magazin. Hamburg 1978, pp. 82-98. ("In the Brazilian jungle on the Rio Tapajós, 12,000 poor devils are looking for gold."). ISSN 0342-8311
- In Search of El Dorado (1983/84) Documentary by Oliver Herbrich
- Os Garimpeiros (1986) Documentary by Gaudenz Meili
Web links
- USGS article on gold prospecting (English)
- "Goldwashing" map of Germany from ZEITmagazin, April 5, 2016
- Gold extraction with borax
Individual evidence
- ↑ History of panning for gold in Rauristal.
- ^ Robert W. Boyle: Gold. History and Genesis of Deposits. Van Nostrand Reinhold, New York 1987, ISBN 0-442-21162-7 .
- ↑ A. Einstein: The cause of the meander formation of the river formation and the so-called Baer's law. In: Naturwiss. 14, 1926, pp. 223-224, reviewed by Karl-Heinz Bernhardt : Teacup cyclones and river meanders - Einstein classic. In: Meeting reports of the Leibniz Society. 78/79, 2005, pp. 81–95, (PDF file)
- ↑ JM West: How to Mine and Prospect for Placer Gold. (= US Bureau of Mines. Information Circular 8517). 1971.
- ↑ JG Stone et al .: Using diamond drilling to evaluate a placer deposit: a case study. In: Mining Engineering. September 1988, pp. 875-880.
- ^ Scott A. Stebbins: Cost Estimation Handbook for Small Placer Mines. (= US Bureau of Mines. Information Circular 9170). 1987.
- ^ RP Fischer, FS Fisher: Interpreting Pan-Concentrate Analyzes of Stream Sediments in Geochemical Exploration for Gold. (= US Geological Survey. Circular 592). 1968.
- ↑ Illegal prospectors: Expensive gold is destroying the rainforest. at: spiegel.de
- ^ Justus Freiherr von Liebig , Johann Christian Poggendorff , Friedrich Wöhler (ed.): Concise dictionary of pure and applied chemistry . Friedrich Vieweg and Son, Braunschweig 1842 ( limited preview in the Google book search).
- ↑ See the gold-mercury phase diagram in: H. Okamoto, TB Massalski: The Au-Hg (Gold Mercury) System. In: Bulletin of Alloy Phase Diagrams. 1989, at springer.com
- ↑ Behind Gold's Glitter: Torn Lands and Pointed Questions. at: nytimes.com. S. 1. (English)
- ↑ Mercury-free gold mining at appelglobal.com
- ↑ gold extraction ( memento of the original from August 16, 2013 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , English, at geology.com
- ↑ Peter WU Appel, Leoncio Na-Oy: The Borax Method of Gold Extraction for Small-Scale Miners. ( Memento of the original from May 31, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: Journal of Health and Pollution. Vol. 2, No. 3, 2012.
- ↑ Filipino Gold Miner's Borax Revolution. ( Memento of the original from October 13, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Blacksmith Institute website , March / April 2012.
- ^ US Bureau of Land Management: Recreational gold prospecting on public land. ( Memento of the original from October 23, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ US Geological Survey: Prospecting for gold in the United States
- ↑ ClickForAustralia.com: Fossicking and gold panning in the Northern Territory.
- ^ Ministry of Economic Development, Crown Minerals: Gold fossicking (recreational gold panning).
- ↑ guldplace.de
- ↑ Swiss Gold Prospector's Association: Recreational Gold Prospecting in Switzerland ( Memento of the original from December 20, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Gold locations or gold deposits in Germany map + location , at gold-barren.eu
- ↑ Gold washing. ZEITmagazin, April 5, 2016, accessed on February 4, 2017 .
- ↑ André Thieme (ed.): Duke Albrecht der Beherzte (1443–1500). A Saxon prince in the empire and in Europe . Böhlau, Vienna 2002, ISBN 3-412-03501-7 ( limited preview in the Google book search).
- ^ Karl Friedrich Vollrath Hoffmann (Ed.): Europe and its residents . J. Scheidle's publishing expedition, Leipzig / Stuttgart 1835 ( limited preview in the Google book search).
- ^ Karl Friedrich Vollrath Hoffmann (Ed.): Europe and its residents . J.Scheidle's publishing expedition, Leipzig / Stuttgart 1835 ( limited preview in the Google book search).
- ^ Hainzenberg gold mine .
- ^ Fritz Gruber: The mining areas in the Bockharttal up to the 17th century. In: Communications from the Society for Regional Studies in Salzburg. Volume 142, 2002, pp. 251-265 ( PDF on ZOBODAT ).
- ^ KK Statistische Central-Commission (Hrsg.): Mittheilungen from the field of statistics . Kaiserlich-Königliche Staatsdruckerei on commission at Prandel & Ewald, Vienna 1835 ( limited preview in the Google book search).
- ↑ Video: British are looking for gold in the Lungau. In: Salzburger Nachrichten. August 30, 2013.
- ↑ The search for gold continues. In: Salzburger Nachrichten. December 9, 2013.
- ↑ Tauern gold. In: Salzburg Wiki. Retrieved September 4, 2013.
- ↑ a b c d e f g h R.J. Mayrhofer: Old gold and silver ore mines in Lower Austria , PDF file
- ^ A b c Anne-Marie Dubler : Precious Metals. In: Historical Lexicon of Switzerland . November 27, 2008 , accessed June 5, 2019 .
- ↑ André Thieme (ed.): Duke Albrecht der Beherzte (1443–1500). A Saxon prince in the empire and in Europe . Böhlau, Vienna 2002, ISBN 3-412-03501-7 ( limited preview in the Google book search).
- ^ Karl Friedrich Vollrath Hoffmann (Ed.): Europe and its residents . J.Scheidle's publishing expedition, Leipzig / Stuttgart 1835 ( limited preview in the Google book search).
- ↑ Heinz Fengler,…: transpress-Lexikon numismatics. (1976), p. 95
- ^ KK Statistische Central-Commission (Hrsg.): Mittheilungen from the field of statistics . Kaiserlich-Königliche Staatsdruckerei on commission at Prandel & Ewald, Vienna 1835 ( limited preview in the Google book search).
- ↑ Everything that glitters is gold. at: nachrichten.at
- ↑ a b Gold and Silver in the Baselbieter Namenschatz. In: Annual report 2010 of the Baselland Foundation for Location and Field Name Research. Ischlag, May 2011. (PDF file) ( Memento of the original from March 6, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Herbert Haupt: From passion to beauty. Prince Karl Eusebius of Liechtenstein 1611–1684. Source volume . Böhlau, Vienna 1998, ISBN 3-205-98874-4 ( full text in the Google book search).
- ^ Ian Blanchard: Mining, Metallurgy and Minting in the Middle Ages . Franz Steiner, Stuttgart 2005, ISBN 3-515-08704-4 ( full text in the Google book search).
- ^ Gustav Albiez: Mining field names in the Black Forest. In: The cut. Volume 18. No. 5., p. 5.
