To learn morevisitthe next installments in the Geology series:Weathering and Acid Rock Drainage. For example, oil and gas are made by a combination of sedimentary processes which trap and bury plant and animal remains, and then metamorphic processes which heat and change the remains into deposits of oil and gas. Revenues from the petroleum sector are significantly higher, at over $100 billion per year. why it was the first metal discovered and used by humans. This can be done by opencast quarrying or underground mining. These have mostly been mined in the past. Heavier gold, platinum, tin and uranium minerals settle to the bottom of the streams and rivers where they are concentrated. Physical Geology by Steven Earle is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted. To find out how important minerals are in our everyday life read Why we need minerals. You have reached the end of the main content. Landslide Concept, Causes & Facts | What is a Landslide? The magmas from which these deposits form are of mafic or ultramafic composition (derived from the mantle), and therefore they have relatively high nickel and copper contents to begin with (as much as 100 times more than normal rocks in the case of nickel). During migration, the oil-water system breaks-up with the oil floating on the water. Canada has some of the largest mining districts and deposits in the world, and for the past 150 years, we have been one of the most important suppliers of metals. Biorhythms History & Formula | What is a Biorhythm? Porphyry deposits are the most important source of copper and molybdenum in British Columbia, the western United States, and Central and South America. When a resource is confidently located and the ore grade has been assessed, companies then begin to plan their mining operation. As you can tell, it's a long process to get to the point of actually mining the materials from the Earth. The tailings pond at the Myra Falls Mine on Vancouver Island is shown in Figure 20.12, and the settling ponds for waste water from the concentrator are shown in Figure 20.13. All rights reserved. Peat deposits have long been used (particularly in Northern Europe) as a source of fuel. Image credit: gadigal yilimung (shield) madeby UncleCharlesChickaMadden. For example the most abundant They are currently forming on the sea floor and these are commonly referred to as black smokers. B.C. Working Scholars Bringing Tuition-Free College to the Community, Examine what goes into each of the three main stages of mineral exploration. Alluvial: Detrital material which is transported by a river and usually deposited along the river's pathway, either in the riverbed itself or on its floodplain. They are ancient volcanic structures, most commonly collapsed craters and calderas. In much the same way, geologists have to drill these cores to probe inside the Earth and learn where the boundaries of the deposit are. It comes out of the concentrator as a wet slurry and must be stored near the mine, in most cases, in a tailings pond. Imagine that you are trying to locate the extent of filling in a jelly doughnut using only a straw. Mineral deposits can only be extracted where they are found. These must be carefully planned and designed so that the workers can safely extract as much valuable ore as possible. magnetite minerals cameo discordia It has undergone numerous episodes of deformation and metamorphism with the ore bodies themselves being strongly folded, faulted and metamorphosed. Because some metals are so valuable, grades below 1% can still be worthwhile mining investments! In this way, it is possible to focus the mining on the ore body itself. (c) Expenditures related to the development of mineral res. Look back through the deposit-type descriptions above and complete the following table, describing which of those deposit types depend on a source of heat for their formation, and why. today for this to be feasible. Certain minerals can also be extracted by pumping. Those that have the lowest boiling temperature become accumulations of natural gas which, being lighter than the oil, forms a gas-cap on top of the oil accumulation. When pyrite is exposed to oxygen and water, it generates sulphuric acid also known as acid rock drainage (ARD). Some of these deposits occur as pipe-like bodies or breccia pipes. For thick, economically viable evaporite layers to be deposited, a continuous evaporation-replenishment system must operate. flashcard sets, {{courseNav.course.topics.length}} chapters | There are several different types of uranium deposits, but some of the largest and richest are those within the Athabasca Basin of northern Saskatchewan. The origin of natural oil is still disputed but most geologists believe that it is derived from organic material by decay. lead to local concentration of metal minerals, metals are distributed Before companies can begin paying for costly surveys, geologists decide on a large area that is likely to have the mineral deposit of interest. 
in Australia, Canada and Brazil. 's' : ''}}. Fireclay is a fossil clay-rich soil associated with coal deposits. magmas). (a) Expenditure for the acquisition of rights to explore. The placer deposits usually form from primary deposits in which the ore mineral is widely disseminated and uneconomic. are called banded iron formations and are a major source of iron ore China Clay: deposits of kaolin produced by hydrothermal decomposition or deep weathering of feldspar minerals in granites. Mineral deposits come in many shapes and sizes depending on where and how the mineral was concentrated. The metals and the sulphur are leached out of the sea-floor rocks by convecting groundwater driven by the volcanic heat, and then quickly precipitated where that hot water enters the cold seawater, causing it to cool suddenly and change chemically. minerals like sulphides form but it is important to rememberthat not all This is because without metals our best tools are made of Volcanic rocks are divided into three main types: basaltic, volcaniclastic and pyroclastic. deformation) or chemical (i.e. The main types of geological ore deposits of importance can be divided into: Geologists are always searching for more ore deposits to meet constant demand. The Broken Hill lode in far western New South Wales is an excellent example of this. The most common iron ore minerals are hematite, lepidocrocite and goethite while the most common manganese ore minerals are braunite, manganite and hausmannite. Geoscience (also known as earth sciences and geology) is the study of the Earth and includes all non-living parts of our environment, and everything below the Earth's surface. Despite all of the mines that have been active throughout time, there are innumerable failed exploration projects that did not result in final resource production. Mining has always been a major part of Canadas economy. For a mineral to be concentrated in a placer deposit, it must be resistant to weathering and erosion and have a relatively high specific gravity. containing sulphide minerals like pyrite are exposed at the earths It can be understood as the amount of metal per unit rock. Creating a giant hole in the ground is generally cheaper than making an underground mine, but it is also less precise, so it is necessary to mine a lot of waste rock along with the ore. For a variety of reasons, thermal energy (heat) from within Earth is critical in the formation of many types of ore deposits. They generally occur as lens-shaped bodies and are most commonly mined by open-cut methods. Some of these laterites also contain elevated levels of the platinum-group elements which are an important by-product of the mining. Metals are not usable as Examples are the deposits at Kidd Creek, Ontario, Flin Flon on the Manitoba-Saskatchewan border, Britannia on Howe Sound, and Myra Falls (within Strathcona Park) on Vancouver Island. Tar pits: small areas where soft asphaltic tar wells up to the surface and fills a hollow. As many ore deposits formed many hundreds to thousands of millions of years ago, many have experienced numerous episodes of deformation and metamorphism which left them with few characteristics of their original form. Essentially this means that per tonne of rock lower than the value of metal per tonne of rock. Apart from gold, air and water, is removed and replaced by oxygen. Mineral exploration is undertaken in order to find mineral deposits that are suitable for commercial exploitation. For instance, copper often forms from hydrothermal fluids near volcanic activity. Simple weathering of While the resource exploration is performed by trained geologists, the actual mine development and operations are overseen by mining engineers, who are trained to design safe and effective ways to best extract a deposit. examples include several large deposits within the Highland Valley mine (Figure 20.1) and numerous other deposits scattered around the central part of the province. Read the Guide to Mineral Safeguarding in England. metals only came into use when technology was devised to remove the To find out more on the global trade of minerals, why trade is necessary, changes in global minerals trade and the UK's minerals trade position read Mineral Matters 4: Minerals trade a global picture. Peat is a partially decomposed mass of vegetation that has grown in a shallow lake or marsh. Rock Strata Overview & Importance | What is Rock Strata? The settling out of heavy minerals like sulphides or chromium oxides to the bottom of a chamber of cooling molten magma. {{courseNav.course.mDynamicIntFields.lessonCount}} lessons amount of metal per ton of rock), easy access to infrastructure such as roads and rail for transportation, Gangue minerals: quartz (usually cryptocrystalline), baryte, calcite, aragonite, Manganese: pyrolusite, romanechite, rhodochrosite, tectonic setting in which the deposit occurs, geological setting of the mineral deposit, genetic model for the origin of the ore deposit, silica occurring as quartz (most often forming comb-like aggregates), amethyst, opal, chalcedony and cristobalite. Fossil placer deposits are also of great importance, with the world's largest gold deposit, the Witwatersrand reefs of South Africa, an excellent example. The pressure of this gas cap on the overlying strata and the upward pressure of any underlying water below the oil layer are used to drive the oil towards the surface without the need for pumping. During the ore-forming process, some of the original minerals in these rocks are altered to potassium feldspar, biotite, epidote, and various clay minerals. These gold deposits are generally of large tonnage (millions of tonnes), and low-grade (commonly 1.5 - 3 g/T), confined to very narrow, mostly steeply-plunging near-vertical structures and are sulfide-deficient. ; the nickel smelter at Thompson, Manitoba; numerous steel smelters in Ontario, along with several other refining operations for nickel, copper, zinc, and uranium; aluminum refineries in Quebec; and a lead smelter in New Brunswick. The formation of these deposits is linked to regional-scale processes at mid-crustal levels during regional metamorphism. Alluvial or placer river deposits are formed by the ravages of weathering on earth. Mineral Matters 13: Safeguarding our minerals supply. The oil-bearing strata itself has to be pervious or porous so that the oil can flow freely through it. Therefore, more complex techniques have been developed to locate new deposits. These deposits are very large in size (thousands of millions of tons) and are usually mined by open-cut methods. The natural weathering of sulphides also has environmental and social implications which Mining Focus will illuminate. Which of the following expenditures would never qualify as an exploration and evaluation asset? Minerals can be found throughout the world in the earth's crust but usually in such small amounts that they not worth extracting. Most of the world's iron and manganese are derived from deposits of this type. Combined processes of compaction (from overlying sediments) and slight heating converts this organic material to black coal. A variety of methods may be used, including remote sensing (aerial photography and satellite images), geochemical surveys (looking for chemicals in soil and water which indicate certain minerals are present). The most common evaporite deposits are salts (most commonly sylvite and halite), gypsum, and nitrates. grade (i.e. Once a mineral deposit has been found it has to be extracted from the ground to access the valuable minerals it contains. Only with the help of certain geological processes are minerals concentrated into economically viable deposits. Other sulphide minerals are commonly present within the ore, especially pyrite. They are called massive sulphide deposits because the sulphide minerals (including pyrite (FeS2) , sphalerite (ZnS), chalcopyrite (CuFeS2), and galena (PbS)) are generally present in very high concentrations (making up the majority of the rock in some cases). For the other elements in the list, the concentration factors are much higher. wood, bone and stone. The next step is to actually begin to drill holes into the Earth to test whether their hypotheses are correct. 
A metal deposit is a body of rock in which one or more metals have been concentrated to the point of being economically viable for recovery. As they are very ancient, most of these deposits have been intensely deformed and metamorphosed. Basic and ultrabasic rocks tend to form laterites while granitic rocks lead to the development of bauxite. naturally occurring sulphide and oxide minerals. For example, the Himalayas are being washed away and levelled at the rate of 1 kilometer of elevation every million years. For example, the First Nations of British Columbia extracted obsidian from volcanic regions for tools and traded it up and down the coast. Salt domes: under conditions of high pressure, salt deforms plastically and behaves like a magma deforming and piercing through the overlying sediments. Thus, geologists will often look for this type of alteration as a clue that there may be copper nearby. mineral resources development explain pakistan economic role important found Also visible in the foreground of Figure 20.12 is a pile of waste rock, which is non-ore rock that was mined in order to access the ore. Once geologists are certain that there is a good potential for valuable economic deposits to be in a certain area, they will begin a more targeted reconnaissance mission. flashcard set{{course.flashcardSetCoun > 1 ? Concentration occurs when the surrounding rock is eroded away and the heavy ore mineral becomes concentrated by erosional processes. These deposits are believed to have formed in shallow marine basins and are confined to Proterozoic rock sequences. Geologic Time Scale Overview, Periods & Eons | What is Geologic Time Scale? The majority of that was split roughly equally among gold, iron, copper, and potash, with important but lesser amounts from nickel and diamonds (Figure 20.3). Create your account, 21 chapters | Phosphate deposits are of three main types: Coal is a general name given to stratified accumulations of carbonaceous material derived from vegetation. In August 2014, the tailings pond at the Mt. Minerals are concentrated by igneous, sedimentary and metamorphic processes: The different ways to concentrate minerals can often work together. What are some of its success? sulphur as minerals called sulphides or oxygen as minerals called For example German scientist Fritz Haber considered The next stage is resource evaluation, where geologists extract samples from the region by drilling into the Earth to better understand the nature and location of the deposit. Most mines have concentrators on site because it is relatively simple to separate ore minerals from non-ore minerals and thus significantly reduce the costs and other implications of transportation. The final stage is development and production, which is the building of the mine and extraction of the mineral deposit. This gravitational process results in concentrations ofheavy minerals at the base of the chamber. 
Grade is the concentration of the metal in a body of rock and is normally expressed as a percent. called a regolith or. sold (which uses ore from overseas); the lead-zinc smelter in Trail, B.C. The mineralogy of phosphate deposits is very complex. The way minerals are transported depends on their value and bulk. An exception is gold which occurs in its pure metallic form, which is Then, during the dry season, the solution containing the leached ions is drawn towards the surface by capillary action where it evaporates leaving behind salts that are washed away in the next wet season. This is why stream beds, ancient and current, are where prospectors look for gold nuggets and other heavy metal minerals. In the case of valuable metals, geologists are often looking for specific clues, such as minerals and high concentrations of certain elements. In Australia, most Archaean lode gold deposits occur in the Norseman-Wiluna greenstone belt of Western Australia (this includes the famous Kalgoorlie Golden Mile containing the Super Pit, an open-cut gold operation that has dimensions of 3 km x 1 km x 1 km). | 13 The iron and manganese ores occur as distinct sedimentary layers alternating with iron and manganese-poor sedimentary layers - the whole mass is sometimes mined. As we learned in a different lesson in this course, we only care about mineral deposits because they have economic potential in our society, meaning they are useful enough to become valuable. For gold, its 2,000 times and for silver its around 10,000 times. These deposits are related to convergent-margin tectonic settings such as that of the Andes, South America. Gold is present as minute flakes of native gold. Most oil shale deposits are associated with coal. Join us, volunteer and be a part of our journey of discovery! Once our geologist teams have targeted a specific area for having all of the required clues of valuable mineral deposits, they then begin a greater detailed investigation into the economic potential of the area. Peat contains recognisable vegetable material but very little mineral material. Important deposits of gold, mercury, antimony, copper and base metals are of this type. Unlike many other metals, which are economically viable at grades of around 1% or even much less, iron deposits are only viable if the grades are in the order of 50% iron and if they are very large. They do this by examining existing maps and data, performing reconnaissance surveys, and looking for clues, such as alteration. These are very important as they are our main source for the elements titanium and zirconium. Home | Downloads | Glossary | Contact us | Site map | Videos | Help. For example, the most common ore of copper is chalcopyrite (CuFeS2). Try refreshing the page, or contact customer support. processes which result in the concentration of metal-bearing minerals, creating mineral deposits. It is not economic to transport heavy low-cost minerals like aggregates over long distances, whereas expensive minerals, like metals or oil, can be transported internationally. metal minerals are valuable. - Definition & Importance. These are made of alluvial, colluvial and eluvial material, which contain economic quantities of some valuable minerals: The most common placer deposits are those of gold, platinum, group minerals, gemstones, tin, rutile, monazite and zircon. Metals rarely occur in their pure After minerals have been extracted from the ground they are converted to a form that is useful to us. Receive the latest news on events, exhibitions, scienceresearch and specialoffers. surface they rust because the sulphur in sulphides, when exposed to Peat deposits may be tens of metres thick and cover a large area. Although this waste rock contains little or no ore minerals, at many mines it contains up to a few percent pyrite. An error occurred trying to load this video. Some of the gold deposits of British Columbia (such as in the Eskay Creek area adjacent to the Alaska panhandle), and many of the other gold deposits situated along the western edge of both South and North America are of the vein type shown in Figure 20.6, and are related to nearby magma bodies. In the past, mineral deposits were found by geologists mapping the surface of the Earth looking for clues of valuable mineralization. In tropical environments rocks that do not The island of Nauru in the Pacific is one of the world's largest deposits of phosphorite and has been mined since at least the 1950s. Oil usually contains many different hydrocarbons that have differing boiling temperatures. Epithermal gold deposits occur over a considerable length (tens of kilometres) but are of limited vertical extent (on average, 350 m). However, most oxidised zones have been mined in the past because they formed outcrops of easily identifiable stained gossans. Peat deposits form in areas of high rainfall, usually under temperate to cold climatic conditions. marine basins) though some has also formed in estuarine and deltaic environments. (b) Expenditure for exploratory drilling. that makes it economic to mine. Since the majority of magnetic mineral deposits are more dense than average bedrock, all of these methods are basically looking for physical anomalies that may suggest that a dense metal-rich deposit is present at depth. throughout the earth, even in seawater and organisms, including our Because of their cost and the economies of scale, there are far fewer refineries than there are mines. Many factors control the economic viability of an ore deposit but the most important are: The region above the water-table in an ore deposit is known as the oxidised zone as it is the zone of oxidation of the primary ore minerals. themselves have sufficient metal to be mined are weathered to a soil In New Caledonia, these deposits are extensively mined and the main nickel-bearing phases are amorphous nickel silicates. The heavy nickel and copper sulphide minerals are then concentrated further still by gravity segregation (i.e., crystals settling toward the bottom of the magma chamber). An "ore However, with relatively large ore bodies, it may be necessary to leave some pillars to hold up the roof. The remaining material is usually just iron and aluminium oxides which are concentrated. Water Resource Issues: Activities Affecting the Water Supply, Extraction and Processing of Minerals & the Environmental Impacts of Mineral Use. This circulation of hot fluids severely alters the nearby rocks. These include the two main types of gold deposits - epithermal and lode gold deposits along with replacement deposits in calcareous sequences (Mississippi Valley deposits), base-metal vein deposits and replacement skarn deposits. With leaching under the right pH conditions, silica is also dissolved and removed from the system. The tailings and the waste rock at most mines are an environmental liability because they contain pyrite plus small amounts of ore minerals. Much of the copper, zinc, lead, silver, and gold mined in Canada is mined from volcanichosted massive sulphide (VHMS) deposits associated with submarine volcanism (VMS deposits). as the oxide mineral hematite. There is a very strong structural control to Archaean lode gold deposits with most being related to regional fault systems. Most of the nickel mined in Canada comes from magmatic deposits such as those in Sudbury (Ontario), Thompson (Manitoba) (Figure 20.4), and Voiseys Bay (Labrador). They are called porphyry because upper crustal stocks are typically porphyritic in texture, the result of a two-stage cooling process. Most of the worlds major iron deposits are of the banded iron formation type, and most of these formed during the initial oxygenation of Earths atmosphere between 2,400 and 1,800 Ma.
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