Misplaced Pages

#101898

83-503: Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, and final reclamation or restoration of the land after the mine is closed. Mining materials are often obtained from ore bodies, lodes , veins , seams , reefs , or placer deposits . The exploitation of these deposits for raw materials is dependent on investment, labor, energy, refining, and transportation cost. Mining operations can create

166-628: A close-packed cubic unit cell much like the mineral halite of the halide mineral group. Zinc, cadmium , iron , copper , antimony , arsenic , bismuth and selenium also occur in variable amounts in galena. Selenium substitutes for sulfur in the structure constituting a solid solution series. The lead telluride mineral altaite has the same crystal structure as galena. Within the weathering or oxidation zone galena alters to anglesite (lead sulfate) or cerussite (lead carbonate). Galena exposed to acid mine drainage can be oxidized to anglesite by naturally occurring bacteria and archaea , in

249-635: A hopper and a shaking screen or trommel which frees the desired minerals from the waste gravel. The minerals are then concentrated using sluices or jigs. Large drills are used to sink shafts, excavate stopes, and obtain samples for analysis. Trams are used to transport miners, minerals and waste. Lifts carry miners into and out of mines, and move rock and ore out, and machinery in and out, of underground mines. Huge trucks, shovels and cranes are employed in surface mining to move large quantities of overburden and ore. Processing plants use large crushers, mills, reactors, roasters and other equipment to consolidate

332-873: A mass of actual rock. Both types of ore deposit, placer or lode, are mined by both surface and underground methods. Some mining, including much of the rare earth elements and uranium mining , is done by less-common methods, such as in-situ leaching : this technique involves digging neither at the surface nor underground. The extraction of target minerals by this technique requires that they be soluble, e.g., potash , potassium chloride , sodium chloride , sodium sulfate , which dissolve in water. Some minerals, such as copper minerals and uranium oxide , require acid or carbonate solutions to dissolve. Explosives in Mining Explosives have been used in surface mining and sub-surface mining to blast out rock and ore intended for processing. The most common explosive used in mining

415-421: A mining claim. The traditional methods of prospecting involved combing through the countryside, often through creek beds and along ridgelines and hilltops, often on hands and knees looking for signs of mineralization in the outcrop. In the case of gold, all streams in an area would be panned at the appropriate trap sites looking for a show of 'colour' or gold in the river trail. Once a small occurrence or show

498-426: A mining operation. Once the analysis determines a given ore body is worth recovering, development begins to create access to the ore body. The mine buildings and processing plants are built, and any necessary equipment is obtained. The operation of the mine to recover the ore begins and continues as long as the company operating the mine finds it economical to do so. Once all the ore that the mine can produce profitably

581-503: A more sustainable future, the demand for metals is set to skyrocket. Between 2022 and 2050, an estimated 7 billion metric tons of metals will need to be extracted. Steel will account for the largest portion of this total at 5 billion tons, followed by aluminum at 950 million tons, copper at 650 million tons, graphite at 170 million tons, nickel at 100 million tons, and other metals. Notably, the energy expenditure required to extract these metals will soon surpass that of coal mining, highlighting

664-763: A negative environmental impact, both during the mining activity and after the mine has closed. Hence, most of the world's nations have passed regulations to decrease the impact; however, the outsized role of mining in generating business for often rural, remote or economically depressed communities means that governments often fail to fully enforce such regulations. Work safety has long been a concern as well, and where enforced, modern practices have significantly improved safety in mines. Unregulated, poorly regulated or illegal mining , especially in developing economies , frequently contributes to local human rights violations and environmental conflicts . Mining can also perpetuate political instability through resource conflicts . Since

747-482: A process similar to bioleaching . One of the oldest uses of galena was to produce kohl , an eye cosmetic now regarded as toxic due to the risk of lead poisoning . In Ancient Egypt , this was applied around the eyes to reduce the glare of the desert sun and to repel flies, which were a potential source of disease. In pre-Columbian North America, galena was used by indigenous peoples as an ingredient in decorative paints and cosmetics, and widely traded throughout

830-407: A strong inducement to extract these metals or to lease the deposits and collect royalties from mine operators. English, German , and Dutch capital combined to finance extraction and refining . Hundreds of German technicians and skilled workers were brought over; in 1642 a colony of 4,000 foreigners was mining and smelting copper at Keswick in the northwestern mountains. Use of water power in

913-404: A triangular head, with a very sharp point. The introduction of modern gravity and magnetic surveying methods has greatly facilitated the prospecting process. Airborne gravimeters and magnetometers can collect data from vast areas and highlight anomalous geologic features. Three-dimensional inversions of audio-magnetotellurics (AMT) is used to find conductive materials up to a few kilometers into

SECTION 10

#1732848674102

996-632: Is ammonium nitrate . Between 1870 and 1920, in Queensland Australia, an increase in mining accidents lead to more safety measures surrounding the use of explosives for mining. In the United States of America, between 1990 and 1999, about 22.3 billion kilograms of explosives were used in mining quarrying and other industries; Moreover " coal mining used 66.4%, nonmetal mining and quarrying 13.5%, metal mining 10.4%, construction 7.1%, and all other users 2.6%". Artisanal and small-scale mining (ASM)

1079-429: Is a semiconductor with a small band gap of about 0.4  eV , which found use in early wireless communication systems. It was used as the crystal in crystal radio receivers, in which it was used as a point-contact diode capable of rectifying alternating current to detect the radio signals. The galena crystal was used with a sharp wire, known as a " cat's whisker ", in contact with it. In modern times, galena

1162-810: Is a blanket term for a type of subsistence mining involving a miner who may or may not be officially employed by a mining company but works independently, mining minerals using their own resources, usually by hand. While there is no completely coherent definition for ASM, artisanal mining generally includes miners who are not officially employed by a mining company and use their own resources to mine. As such, they are part of an informal economy . ASM also includes, in small-scale mining, enterprises or individuals that employ workers for mining, but who generally still use similar manually-intensive methods as artisanal miners (such as working with hand tools). In addition, ASM can be characterized as distinct from large-scale mining (LSM) by less efficient extraction of pure minerals from

1245-476: Is done by removing surface vegetation, dirt, and bedrock to reach buried ore deposits. Techniques of surface mining include: open-pit mining , which is the recovery of materials from an open pit in the ground; quarrying , identical to open-pit mining except that it refers to sand, stone and clay; strip mining , which consists of stripping surface layers off to reveal ore underneath; and mountaintop removal , commonly associated with coal mining, which involves taking

1328-426: Is found in hydrothermal veins in association with sphalerite , marcasite , chalcopyrite , cerussite , anglesite , dolomite , calcite , quartz , barite , and fluorite . It is also found in association with sphalerite in low-temperature lead- zinc deposits within limestone beds. Minor amounts are found in contact metamorphic zones, in pegmatites , and disseminated in sedimentary rock. In some deposits,

1411-498: Is found in hydrothermal deposits emplaced around 1680 million years ago, which have since been heavily metamorphosed. The largest documented crystal of galena is composite cubo-octahedra from the Great Laxey Mine , Isle of Man , measuring 25 cm × 25 cm × 25 cm (10 in × 10 in × 10 in). Galena is the official state mineral of the U.S. states of Kansas, Missouri, and Wisconsin;

1494-612: Is mining upward, creating a sloping underground room, long wall mining , which is grinding a long ore surface underground, and room and pillar mining, which is removing ore from rooms while leaving pillars in place to support the roof of the room. Room and pillar mining often leads to retreat mining , in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby loosening more ore. Additional sub-surface mining methods include hard rock mining , bore hole mining, drift and fill mining, long hole slope mining, sub level caving, and block caving . Heavy machinery

1577-483: Is much more common, and produces, for example, 85% of minerals (excluding petroleum and natural gas) in the United States, including 98% of metallic ores. Targets are divided into two general categories of materials: placer deposits , consisting of valuable minerals contained within river gravels, beach sands, and other unconsolidated materials ; and lode deposits , where valuable minerals are found in veins, in layers, or in mineral grains generally distributed throughout

1660-413: Is not of immediate interest to the miner. The total movement of ore and waste constitutes the mining process. Often more waste than ore is mined during the life of a mine, depending on the nature and location of the ore body. Waste removal and placement is a major cost to the mining operator, so a detailed characterization of the waste material forms an essential part of the geological exploration program for

1743-584: Is recovered, reclamation can begin, to make the land used by the mine suitable for future use. Technical and economic challenges notwithstanding, successful mine development must also address human factors. Working conditions are paramount to success, especially with regard to exposures to dusts, radiation, noise, explosives hazards, and vibration, as well as illumination standards. Mining today increasingly must address environmental and community impacts, including psychological and sociological dimensions. Thus, mining educator Frank T. M. White (1909–1971), broadened

SECTION 20

#1732848674102

1826-632: Is the largest producer of diamonds in Africa, with an estimated 12 million carats in 2019. Other types of mining reserves in Africa include cobalt , bauxite , iron ore , coal, and copper . Gold and coal mining started in Australia and New Zealand in the 19th century. Nickel has become important in the economy of New Caledonia . In Fiji , in 1934, the Emperor Gold Mining Company Ltd. established operations at Vatukoula , followed in 1935 by

1909-525: Is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver . Galena is one of the most abundant and widely distributed sulfide minerals . It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite , calcite and fluorite . Galena is the main ore of lead , used since ancient times, since lead can be smelted from galena in an ordinary wood fire. Galena typically

1992-423: Is to conduct a feasibility study to evaluate the financial viability, the technical and financial risks, and the robustness of the project. This is when the mining company makes the decision whether to develop the mine or to walk away from the project. This includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability, marketability and payability of

2075-592: Is used for a variety of prospecting, but can mainly be for finding conductive materials. So far these low frequency EM techniques have been proven for geothermal exploration as well as for coal bed methane analysis. Geochemical prospecting involves analyzing the chemical properties of rock samples, drainage sediments, soils, surface and ground waters, mineral separates, atmospheric gases and particulates, and even plants and animals. Properties such as trace element abundances are analyzed systematically to locate anomalies. Galena Galena , also called lead glance ,

2158-419: Is used in mining to explore and develop sites, to remove and stockpile overburden, to break and remove rocks of various hardness and toughness, to process the ore, and to carry out reclamation projects after the mine is closed. Bulldozers, drills, explosives and trucks are all necessary for excavating the land. In the case of placer mining , unconsolidated gravel, or alluvium , is fed into machinery consisting of

2241-511: The Greek author Diodorus Siculus , who mentions fire-setting as one method used to break down the hard rock holding the gold . One of the complexes is shown in one of the earliest known mining maps. The miners crushed the ore and ground it to a fine powder before washing the powder for the gold dust known as the dry and wet attachment processes. Mining in Europe has a very long history. Examples include

2324-974: The Mendips in Somerset , Derbyshire , and Cumberland in England ; the Linares mines in Spain were worked from before the Roman times until the end of the 20th century; the Madan and Rhodope Mountains in Bulgaria ; the Sullivan Mine of British Columbia ; Broken Hill and Mount Isa in Australia ; and the ancient mines of Sardinia . In the United States , it occurs most notably as lead-zinc ore in

2407-590: The Mississippi Valley type deposits of the Lead Belt in southeastern Missouri , which is the largest known deposit, and in the Driftless Area of Illinois , Iowa and Wisconsin , providing the origin of the name of Galena, Illinois , a historical settlement known for the material. Galena also was a major mineral of the zinc -lead mines of the tri-state district around Joplin in southwestern Missouri and

2490-505: The argentiferous galena in the mines of Cartagena ( Cartago Nova ), Linares ( Castulo ), Plasenzuela and Azuaga , among many others. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited. In Great Britain the natives had mined minerals for millennia , but after the Roman conquest , the scale of the operations increased dramatically, as

2573-801: The greenstone of the Langdale axe industry based in the English Lake District . The oldest-known mine on archaeological record is the Ngwenya Mine in Eswatini (Swaziland) , which radiocarbon dating shows to be about 43,000 years old. At this site Paleolithic humans mined hematite to make the red pigment ochre . Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools. Ancient Egyptians mined malachite at Maadi . At first, Egyptians used

Mining - Misplaced Pages Continue

2656-463: The 19th and early 20th century, it was very unlikely that a prospector would retire rich even if he was the one who found the greatest of lodes. For instance Patrick (Paddy) Hannan , who discovered the Golden Mile, Kalgoorlie , died without receiving anywhere near a fraction of the value of the gold contained in the lodes. The same story repeated at Bendigo, Ballarat, Klondike and California . In

2739-504: The 21st century begins, a globalized mining industry of large multinational corporations has arisen. Peak minerals and environmental impacts have also become a concern. Different elements, particularly rare-earth minerals , have begun to increase in demand as a result of new technologies. In 2023, 8.5 billion metric tons of coal were extracted from the Earth's crust. However, as the global economy transitions away from fossil fuels and toward

2822-662: The 7th century to the 14th century. Gold was often traded to Mediterranean economies that demanded gold and could supply salt , even though much of Africa was abundant with salt due to the mines and resources in the Sahara desert . The trading of gold for salt was mostly used to promote trade between the different economies. Since the Great Trek in the 19th century, after, gold and diamond mining in Southern Africa has had major political and economic impacts. The Democratic Republic of Congo

2905-443: The Earth, which has been helpful to locate kimberlite pipes, as well as tungsten and copper. Another relatively new prospecting technique is using low frequency electromagnetic (EM) waves for 'sounding' into the Earth's crust. These low frequency waves will respond differently based on the material they pass through, allowing for analysts to create three-dimensional images of potential ore bodies or volcanic intrusions. This technique

2988-642: The French crown to operate mines in 1733, becoming "the first practical miner on Lake Superior"; seven years later, mining was halted by an outbreak between Sioux and Chippewa tribes. Mining in the United States became widespread in the 19th century, and the United States Congress passed the General Mining Act of 1872 to encourage mining of federal lands. As with the California Gold Rush in

3071-629: The Loloma Gold Mines, N.L., and then by Fiji Mines Development Ltd. (aka Dolphin Mines Ltd.). These developments ushered in a “mining boom”, with gold production rising more than a hundred-fold, from 931.4 oz in 1934 to 107,788.5 oz in 1939, an order of magnitude then comparable to the combined output of New Zealand and Australia's eastern states. During prehistoric times, early Americans mined large amounts of copper along Lake Superior 's Keweenaw Peninsula and in nearby Isle Royale ; metallic copper

3154-477: The Romans needed Britannia 's resources, especially gold , silver , tin , and lead . Roman techniques were not limited to surface mining. They followed the ore veins underground once opencast mining was no longer feasible. At Dolaucothi they stoped out the veins and drove adits through bare rock to drain the stopes. The same adits were also used to ventilate the workings, especially important when fire-setting

3237-588: The Spanish to pulverize ore after being mined. This device was powered by animals and used the same principles used for grain threshing . Much of the knowledge of medieval mining techniques comes from books such as Biringuccio 's De la pirotechnia and probably most importantly from Georg Agricola 's De re metallica (1556). These books detail many different mining methods used in German and Saxon mines. A prime issue in medieval mines, which Agricola explains in detail,

3320-729: The Umm el-Sawwan site; gypsum was used to make funerary items for private tombs. Other minerals mined in Egypt from the Old Kingdom (2649-2134 BC) until the Roman Period (30 BC-AD 395) including granite , sandstone , limestone , basalt , travertine , gneiss , galena , and amethyst . Mining in Egypt occurred in the earliest dynasties. The gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt. These mines are described by

3403-563: The United States and Canada, prospectors were lured by the promise of gold , silver , and other precious metals . They traveled across the mountains of the American West , carrying picks, shovels and gold pans . The majority of early prospectors had no training and relied mainly on luck to discover deposits. Other gold rushes occurred in Papua New Guinea, Australia at least four times, Fiji, South Africa and South America. In all cases,

Mining - Misplaced Pages Continue

3486-592: The adjoining areas of Kansas and Oklahoma . Galena is also an important ore mineral in the silver mining regions of Colorado , Idaho , Utah and Montana . Of the latter, the Coeur d'Alene district of northern Idaho was most prominent. Australia is the world's leading producer of lead as of 2021, most of which is extracted as galena. Argentiferous galena was accidentally discovered at Glen Osmond in 1841, and additional deposits were discovered near Broken Hill in 1876 and at Mount Isa in 1923. Most galena in Australia

3569-623: The beginning of civilization, people have used stone , clay and, later, metals found close to the Earth's surface. These were used to make early tools and weapons; for example, high quality flint found in northern France , southern England and Poland was used to create flint tools . Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Graves and Krzemionki are especially famous, and like most other flint mines, are Neolithic in origin (c. 4000–3000 BC). Other hard rocks mined or collected for axes included

3652-519: The bright green malachite stones for ornamentations and pottery . Later, between 2613 and 2494 BC, large building projects required expeditions abroad to the area of Wadi Maghareh in order to secure minerals and other resources not available in Egypt itself. Quarries for turquoise and copper were also found at Wadi Hammamat , Tura , Aswan and various other Nubian sites on the Sinai Peninsula and at Timna . Quarries for gypsum were found at

3735-416: The cutter-head is progressively launched further into the coal seam. High wall mining can produce thousands of tons of coal in contour-strip operations with narrow benches, previously mined areas, trench mine applications and steep-dip seams. Sub-surface mining consists of digging tunnels or shafts into the earth to reach buried ore deposits. Ore, for processing, and waste rock, for disposal, are brought to

3818-528: The eastern United States. Traces of galena are frequently found at the Mississippian city at Kincaid Mounds in present-day Illinois. The galena used at the site originated from deposits in southeastern and central Missouri and the Upper Mississippi Valley. Galena is the primary ore of lead, and is often mined for its silver content. It is used as a source of lead in ceramic glaze . Galena

3901-697: The focus to the “total environment of mining”, including reference to community development around mining, and how mining is portrayed to an urban society, which depends on the industry, although seemingly unaware of this dependency. He stated, “[I]n the past, mining engineers have not been called upon to study the psychological, sociological and personal problems of their own industry – aspects that nowadays are assuming tremendous importance. The mining engineer must rapidly expand his knowledge and his influence into these newer fields.” Mining techniques can be divided into two common excavation types: surface mining and sub-surface (underground) mining . Today, surface mining

3984-480: The form of water mills was extensive. The water mills were employed in crushing ore, raising ore from shafts, and ventilating galleries by powering giant bellows . Black powder was first used in mining in Selmecbánya , Kingdom of Hungary (now Banská Štiavnica , Slovakia) in 1627. Black powder allowed blasting of rock and earth to loosen and reveal ore veins. Blasting was much faster than fire-setting and allowed

4067-569: The former mining communities of Galena, Kansas , Galena, Illinois , Galena, South Dakota and Galena, Alaska , take their names from deposits of this mineral. Galena belongs to the octahedral sulfide group of minerals that have metal ions in octahedral positions, such as the iron sulfide pyrrhotite and the nickel arsenide niccolite . The galena group is named after its most common member, with other isometric members that include manganese bearing alabandite and niningerite . Divalent lead (Pb) cations and sulfur (S) anions form

4150-645: The galena contains up to 0.5% silver , a byproduct that far surpasses the main lead ore in revenue. In these deposits significant amounts of silver occur as included silver sulfide mineral phases or as limited silver in solid solution within the galena structure. These argentiferous galenas have long been an important ore of silver. Silver-bearing galena is almost entirely of hydrothermal origin; galena in lead-zinc deposits contains little silver. Galena deposits are found worldwide in various environments. Noted deposits include those at Freiberg in Saxony ; Cornwall ,

4233-462: The gold rush was sparked by idle prospecting for gold and minerals which, when the prospector was successful, generated 'gold fever' and saw a wave of prospectors comb the countryside. Modern prospectors today rely on training, the study of geology, and prospecting technology. Knowledge of previous prospecting in an area helps in determining location of new prospective areas. Prospecting includes geological mapping , rock assay analysis, and sometimes

SECTION 50

#1732848674102

4316-399: The growing importance of sustainable metal extraction practices. The process of mining from discovery of an ore body through extraction of minerals and finally to returning the land to its natural state consists of several distinct steps. The first is discovery of the ore body, which is carried out through prospecting or exploration to find and then define the extent, location and value of

4399-435: The intuition of the prospector. Prospecting of minerals found in mobile fluids, as is often the case of lithium , adds a "temporal element" to be considered. Metal detectors are invaluable for gold prospectors, as they are quite effective at detecting gold nuggets within the soil down to around 1 metre (3 feet), depending on the acuity of the operator's hearing and skill. Magnetic separators may be useful in separating

4482-464: The magnetic fraction of a heavy mineral sand from the nonmagnetic fraction, which may assist in the panning or sieving of gold from the soil or stream. Prospecting pickaxes are used to scrape at rocks and minerals , obtaining small samples that can be tested for trace amounts of ore . Modern prospecting pickaxes are also sometimes equipped with magnets , to aid in the gathering of ferromagnetic ores. Prospecting pickaxes are usually equipped with

4565-521: The metals due to the difficulties of transporting them, but the copper was eventually traded throughout the continent along major river routes. In the early colonial history of the Americas, "native gold and silver was quickly expropriated and sent back to Spain in fleets of gold- and silver-laden galleons", the gold and silver originating mostly from mines in Central and South America. Turquoise dated at 700 AD

4648-751: The mid-19th century, mining for minerals and precious metals, along with ranching , became a driving factor in the U.S. Westward Expansion to the Pacific coast. With the exploration of the West, mining camps sprang up and "expressed a distinctive spirit, an enduring legacy to the new nation"; Gold Rushers would experience the same problems as the Land Rushers of the transient West that preceded them. Aided by railroads, many people traveled West for work opportunities in mining. Western cities such as Denver and Sacramento originated as mining towns. When new areas were explored, it

4731-492: The mid-sixteenth century. On the continent, mineral deposits belonged to the crown, and this regalian right was stoutly maintained. But in England, royal mining rights were restricted to gold and silver (of which England had virtually no deposits) by a judicial decision of 1568 and a law in 1688. England had iron , zinc , copper , lead , and tin ores. Landlords who owned the base metals and coal under their estates then had

4814-432: The minehead, where the water was stored in large reservoirs and tanks. When a full tank was opened, the flood of water sluiced away the overburden to expose the bedrock underneath and any gold-bearing veins. The rock was then worked by fire-setting to heat the rock, which would be quenched with a stream of water. The resulting thermal shock cracked the rock, enabling it to be removed by further streams of water from

4897-471: The mineral-rich material and extract the desired compounds and metals from the ore. Prospecting Prospecting is the first stage of the geological analysis (followed by exploration ) of a territory. It is the search for minerals , fossils , precious metals, or mineral specimens. It is also known as fossicking . Traditionally prospecting relied on direct observation of mineralization in rock outcrops or in sediments. Modern prospecting also includes

4980-430: The mining of previously impenetrable metals and ores. In 1762, one of the world's first mining academies was established in the same town there. The widespread adoption of agricultural innovations such as the iron plowshare , as well as the growing use of metal as a building material, was also a driving force in the tremendous growth of the iron industry during this period. Inventions like the arrastra were often used by

5063-405: The ore body. This leads to a mathematical resource estimation to estimate the size and grade of the deposit. This estimation is used to conduct a pre-feasibility study to determine the theoretical economics of the ore deposit. This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. The next step

SECTION 60

#1732848674102

5146-462: The ore concentrates, engineering concerns, milling and infrastructure costs, finance and equity requirements, and an analysis of the proposed mine from the initial excavation all the way through to reclamation. The proportion of a deposit that is economically recoverable is dependent on the enrichment factor of the ore in the area. To gain access to the mineral deposit within an area it is often necessary to mine through or remove waste material which

5229-440: The ore, lower wages, decreased occupational safety, benefits, and health standards for miners, and a lack of environmental protection measures. Artisanal miners often undertake the activity of mining seasonally. For example, crops are planted in the rainy season , and mining is pursued in the dry season . However, they also frequently travel to mining areas and work year-round. There are four broad types of ASM: Surface mining

5312-556: The overhead tanks. The Roman miners used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines . Sluicing methods were developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being at Las Medulas , where seven long aqueducts tapped local rivers and sluiced the deposits. The Romans also exploited the silver present in

5395-432: The prospector to move onwards to the next and hopefully bigger and better show. Occasionally, the prospector would strike it rich and be joined by other prospectors to develop a larger-scale mining operation. Although these are thought of as "old" prospecting methods, these techniques are still used today, but usually coupled with more advanced techniques such as geophysical magnetic or gravity surveys. In most countries in

5478-430: The remaining part of a coal seam previously exploited by other surface-mining techniques has too much overburden to be removed but can still be profitably exploited from the side of the artificial cliff made by previous mining. A typical cycle alternates sumping, which undercuts the seam, and shearing, which raises and lowers the cutter-head boom to cut the entire height of the coal seam. As the coal recovery cycle continues,

5561-445: The shafts could no longer be pumped dry with the available technology. Although an increased use of banknotes , credit and copper coins during this period did decrease the value of, and dependence on, precious metals , gold and silver still remained vital to the story of medieval mining. Due to differences in the social structure of society, the increasing extraction of mineral deposits spread from central Europe to England in

5644-556: The silver mines of Laurium , which helped support the Greek city state of Athens . Although they had over 20,000 slaves working them, their technology was essentially identical to their Bronze Age predecessors. At other mines, such as on the island of Thassos , marble was quarried by the Parians after they arrived in the 7th century BC. The marble was shipped away and was later found by archaeologists to have been used in buildings including

5727-473: The surface through the tunnels and shafts. Sub-surface mining can be classified by the type of access shafts used, and the extraction method or the technique used to reach the mineral deposit. Drift mining uses horizontal access tunnels, slope mining uses diagonally sloping access shafts, and shaft mining uses vertical access shafts. Mining in hard and soft rock formations requires different techniques. Other methods include shrinkage stope mining , which

5810-589: The tomb of Amphipolis. Philip II of Macedon , the father of Alexander the Great , captured the gold mines of Mount Pangeo in 357 BC to fund his military campaigns. He also captured gold mines in Thrace for minting coinage, eventually producing 26 tons per year. However, it was the Romans who developed large-scale mining methods, especially the use of large volumes of water brought to the minehead by numerous aqueducts . The water

5893-446: The top of a mountain off to reach ore deposits at depth. Most placer deposits, because they are shallowly buried, are mined by surface methods. Finally, landfill mining involves sites where landfills are excavated and processed. Landfill mining has been thought of as a long-term solution to methane emissions and local pollution. High wall mining, which evolved from auger mining, is another form of surface mining. In high wall mining,

5976-613: The top slats. Many examples of such devices have been found in old Roman mines and some examples are now preserved in the British Museum and the National Museum of Wales . Mining as an industry underwent dramatic changes in medieval Europe . The mining industry in the early Middle Ages was mainly focused on the extraction of copper and iron . Other precious metals were also used, mainly for gilding or coinage. Initially, many metals were obtained through open-pit mining , and ore

6059-553: The use of geologic, geophysical , and geochemical tools to search for anomalies which can narrow the search area. Once an anomaly has been identified and interpreted to be a potential prospect direct observation can then be focused on this area. In some areas a prospector must also stake a claim, meaning they must erect posts with the appropriate placards on all four corners of a desired land they wish to prospect and register this claim before they may take samples. In other areas publicly held lands are open to prospecting without staking

6142-460: The world's gold, followed by the establishment of large mines such as the Mount Morgan Mine , which ran for nearly a hundred years, Broken Hill ore deposit (one of the largest zinc-lead ore deposits), and the iron ore mines at Iron Knob . After declines in production, another boom in mining occurred in the 1960s. In the early 21st century, Australia remains a major world mineral producer. As

6225-466: The world, which was increasingly demanding copper for electrical and household goods. Canada's mining industry grew more slowly than did the United States due to limitations in transportation, capital, and U.S. competition; Ontario was the major producer of the early 20th century with nickel, copper, and gold. Meanwhile, Australia experienced the Australian gold rushes and by the 1850s was producing 40% of

6308-489: Was found, it was then necessary to intensively work the area with pick and shovel, and often via the addition of some simple machinery such as a sluice box, races and winnows, to work the loose soil and rock looking for the appropriate materials (in this case, gold). For most base metal shows, the rock would have been mined by hand and crushed on site, the ore separated from the gangue by hand. These shows were commonly short-lived, exhausted and abandoned quite soon, requiring

6391-610: Was mined in pre-Columbian America; in the Cerillos Mining District in New Mexico , an estimate of "about 15,000 tons of rock had been removed from Mt. Chalchihuitl using stone tools before 1700." In 1727 Louis Denys (Denis) (1675–1741), sieur de La Ronde – brother of Simon-Pierre Denys de Bonaventure and the son-in-law of René Chartier – took command of Fort La Pointe at Chequamegon Bay ; where natives informed him of an island of copper. La Ronde obtained permission from

6474-575: Was primarily extracted from shallow depths, rather than through deep mine shafts. Around the 14th century , the growing use of weapons , armour , stirrups , and horseshoes greatly increased the demand for iron. Medieval knights , for example, were often laden with up to 100 pounds (45 kg) of plate or chain link armour in addition to swords , lances and other weapons. The overwhelming dependency on iron for military purposes spurred iron production and extraction processes. The silver crisis of 1465 occurred when all mines had reached depths at which

6557-400: Was still present near the surface in colonial times. Indigenous peoples used Lake Superior copper from at least 5,000 years ago; copper tools, arrowheads, and other artifacts that were part of an extensive native trade-network have been discovered. In addition, obsidian , flint , and other minerals were mined, worked, and traded. Early French explorers who encountered the sites made no use of

6640-411: Was the removal of water from mining shafts. As miners dug deeper to access new veins, flooding became a very real obstacle. The mining industry became dramatically more efficient and prosperous with the invention of mechanically- and animal-driven pumps. Iron metallurgy in Africa dates back over four thousand years. Gold became an important commodity for Africa during the trans-Saharan gold trade from

6723-403: Was used for a variety of purposes, including removing overburden and rock debris, called hydraulic mining , as well as washing comminuted , or crushed, ores and driving simple machinery. The Romans used hydraulic mining methods on a large scale to prospect for the veins of ore, especially using a now-obsolete form of mining known as hushing . They built numerous aqueducts to supply water to

6806-413: Was used. At other parts of the site, they penetrated the water table and dewatered the mines using several kinds of machines, especially reverse overshot water-wheels . These were used extensively in the copper mines at Rio Tinto in Spain, where one sequence comprised 16 such wheels arranged in pairs, and lifting water about 24 metres (79 ft). They were worked as treadmills with miners standing on

6889-538: Was usually the gold ( placer and then lode ) and then silver that were taken into possession and extracted first. Other metals would often wait for railroads or canals, as coarse gold dust and nuggets do not require smelting and are easy to identify and transport. In the early 20th century, the gold and silver rush to the western United States also stimulated mining for coal as well as base metals such as copper, lead, and iron. Areas in modern Montana, Utah, Arizona, and later Alaska became predominant suppliers of copper to

#101898