Encyclopedia of Global Resources part 77 ppt

The Bushveld intrusion accounts for almost 50 per - cent of the world’s production of vanadium. Stephen C. Hildreth, Jr. Further Reading Best, Myron G. Igneous and Metamorphic Petrology.2d ed. Malden, Mass.: Blackwell, 2003. Brown, Michael, and Tracy Rushmer, eds. Evolution and Differentiation of the Continental Crust. New York: Cambridge University Press, 2006. Evans, Anthony M. Ore Geology and Industrial Minerals: An Introduction. 3d ed. Boston: Blackwell Scientific Publications, 1993. Naldrett, AnthonyJ. MagmaticsSulfide Deposits:Geology, Geochemistry, and Exploration.Berlin: Springer, 2004. Schmincke, Hans-Ulrich.“Magma.” In Volcanism.New York: Springer, 2004. Young, Davis A. Mind over Magma: The Story of Igneous Petrology. Princeton, N.J.: Princeton University Press, 2003. Web Site U.S. Geological Survey Magma, Lava, Lava Flows, Lave Lakes http://vulcan.wr.usgs.gov/Glossary/LavaFlows/ description_lava_flows.html See also: Earth’s crust; Igneous processes, rocks, and mineral deposits; Ophiolites; Pegmatites; Plutonic rocks and mineral deposits; Vanadium; Volcanoes. Magnesium Category: Mineral and other nonliving resources Where Found Magnesium is a widespread and abundant element. Magnesium chloride and magnesium sulfate are pres- ent in dissolved form in seawater and underground brines—these sources accounted for 43 percent of U.S. magnesium compound production in 2008. Magnesium is also found in many minerals, notably magnesite (MgCO 3 ), dolomite (CaMg (CO 3 ) 2 ), and brucite (Mg(OH) 2 ). China, Russia, Israel, Kazakh- stan, Canada, and Brazil are among the main producers. For a number of years, the United States has with - held its magnesium production statistics to avoid disclosure of companies’ proprietary data. Primary Uses Magnesium is used principally in alloys, refractory materials (60 percent of U.S. use), paper, fertilizer, chemicals, and pyrotechnics. As a compound, it can be used as an additive to food, in medicine, and as a sedative. Technical Definition Magnesium (abbreviated Mg), atomic number 12, be- longs to Group IIA of the periodic table of the elements (alkaline-earth metals). It has three stable isotopes and an average molecular weight of 24.312. Pure magnesium is a silver-white, ductile metal that is malleable when heated. A chemically active element, magnesium is a potent reducing agent. Its specific gravity is 1.738 at 20° Celsius, its melting point is 651° Celsius, and its boiling point is 1,100° Celsius. Description, Distribution, and Forms Magnesium in the form of powder or ribbons readily ignites when heated, burning with an intense white light and releasing large amounts of heat while form- ing magnesia (magnesium oxide, MgO). Magnesium reacts with organic halides to produce Grignard reagents, an important class of chemical compounds used in the laboratory. Magnesium is an alkaline-earth metal, a class of hard, heavy metals that are strongly electropositive and chemically reactive. It is the eighth most abundant element; its concentration in the lithosphere is 20,900 grams per metric ton, and the percentage of its ions in seawater is 0.1272. Magnesium’s density (only two-thirds that of aluminum) and the ease with which the element can be machined, cast, forged, and welded contribute to its commercial applications, as do the refractory properties of some of its compounds. China is the leading producer of primary (mined and processed) magnesium (627,000 metric tons in 2007), accounting for nearly 85 percent of magnesium production in the world. Russia and Canada are the world’s other leading producers. However, from 2003 to 2007, Canadian production declined dramatically from 78,000 to 16,300 metric tons. Magnesium isone of themost commonminerals in the Earth’s crust; its principal commercial source, however, is seawater. Extensive terrestrial deposits of magnesium are also found in the form of magnesite and dolomite. Magnesite, a magnesium carbonate, occurs as a hydrothermal alteration of serpentine, 708 • Magnesium Global Resources (Mg,Fe) 3 Si 2 O 5 (OH) 4 , a vein filling and a replacement mineral in carbonate rocks such as dolostone. Dolo- mite, or calcium magnesium carbonate, is the predom- inant mineral in dolostone, a widespread sedimentary rock similar tolimestone. Most dolomites are thought to haveoriginated from partialreplacement of calcium in limestone by magnesium. Magnesium occurs in nature as a component of several common minerals. Im- portant ores include magnesite, a white or grayish mineral found in crystalline or porcelain-like masses; dolomite, a white mineral that resembles limestone; and brucite, a pearly foliated or fibrous mineral that resembles talc. Magnesium silicates are found in as- bestos, serpentine, and talc. Magnesium chloride and magnesium sulfate occur in dissolved form in sea water and natural underground brines. Magnesium is also a constituent of chlorophyll in green plants. History Sir Humphry Davy discovered magnesia in 1808. In 1828, Antoine Bussy isolated pure magnesium by chemical reduction of the chloride, and in 1833, Mi - chael Faraday isolated magnesium electrolytically. The earliest commercial production of the metal may Global Resources Magnesium • 709 Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.Source: Mineral Commodity Summaries, 2009 150,000 105,000 350,000 350,000 170,000 150,000 600,000 Withheld 140,000 Metric Tons of Magnesium Content 2,500,0002,000,0001,500,0001,000,000500,000 United States Slovakia Russia North Korea India Greece Spain Turkey Other countries U.S. data were withheld to avoid disclosure of company proprietary data.Note: 140,000 200,000 100,000 2,000,000China Brazil Austria Australia Magnesium Compounds: World Mine Production, 2008 have been in France during the first half of the nineteenth century, where a modification of the Bussy method wasemployed. Atthis time, magnesiummetal was used primarily in photography. Around 1886, Germany developed an improved production process based on an electrolytic cell method devised by Rob- ert Bunsen in 1852. Germany became the world’s sole source for elemental magnesium. Magnesium alloys were usedin Germany inthe early1900’s inaircraft fu- selages, engineparts, and wheels.In 1915,when a war- time blockade of Germany by the British interrupted the elemental magnesium trade, magnesium production began in the United States. Large-scale use of dolostone as a refractory material also commenced during World War I. In 1941, Dow Chemical Corpora- tion introduced its process for extracting magnesium from seawater. Obtaining Magnesium Magnesium is obtained principally from seawater through theDow seawater process.The water is treated with lime to produce magnesium hydroxide as a precipitate. This precipitate is mixed with hydrochloric acid to form magnesium chloride; the chloride, in turn, is fused and electrolyzed, producing magnesium metal and chlorine gas. From a liter of seawater, approximately 10milligrams ofmagnesium can beex- tracted. Anothercommon methodfor obtainingmag- nesium is the ferrosilicon (Pidgeon) process, which uses dolomite as a raw material. The dolomite is heated to produce magnesia, which is then reduced with an iron-silicon alloy. Uses of Magnesium Dead-burned magnesite, produced by heating the mineral in a kiln at 1,500° to 1,750° Celsius until it contains less than 1 percent carbon dioxide, is a refractory material.Able towithstand contactwith often corrosive substances at high temperatures, refractory materials are used to line furnaces, kilns, reaction ves - sels, and ladles used in the cement, glass, steel, and metallurgical industries. Magnesia refractories are 710 • Magnesium Global Resources Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.Source: Mineral Commodity Summaries, 2009 U.S. data were withheld to avoid disclosure of company proprietary data.Note: 18,000 700,000 30,000 20,000 35,000 2,000 3,000 Withheld Metric Tons 750,000600,000450,000300,000150,000 Ukraine Kazakhstan Israel China Brazil Russia Serbia United States Magnesium Metal: World Primary Production, 2008 materials particularly suited for the basic oxygen fur - naces used in steelmaking. Dead-burned dolomite, produced by heating dolostone or dolomitic limestone at about 1,500° Celsius, isalso a refractory material used for lining metallurgical furnaces. In its elemental state, magnesium is soft and weak; its alloys, however, are sturdier and have a variety of uses. Magnesium is used extensively as an alloy metal, particularly in combinationwith aluminum, zinc,cad- mium, and manganese. Magnesium alloys in general are lightweight, fatigue-resistant, free from brittle- ness, and able to withstand bending stresses; these qualities make magnesium alloys ideal for jet-engine parts, rockets and missiles, luggage frames, cameras, optical instruments, scientific equipment, and porta- ble power tools. Duralumin, a lightweight alloy of aluminum, copper, magnesium, and manganese, is ductile and malleable before its final heat treatment; afterward, its hardness and tensile strength are in- creased. Its properties make duralumin especially useful to the aircraft industry. Magnalium, an alloy of aluminum andmagnesium thatis lighterand easierto work than aluminum, is used in metal mirrors and scientific instruments. Pure magnesium is used in incendiary bombs, sig- nals and flares, thermite fuses, and other pyrotechnic devices. It is an important component of photo- graphic flashbulbs, a deoxidizing agent used in the preparation of some nonferrous metals, a rocket and missile fuel additive, and an agent for chemical syn- thesis. Magnesium reacts with organic halides to form Grignard reagents, an importantclass of extremely reactive chemical compoundsthat are used in synthesiz- ing hydrocarbons, alcohols, carboxylic acids, and other compounds. Magnesium compounds are used in chemicals, ceramics, cosmetics, fertilizer, insula- tion, paper, leather tanning, and textile processing. Epsom salts (magnesium sulfate heptahydrate), milk of magnesia (magnesium hydroxide), and citrate of magnesium are used in medicines. Caustic-calcined magnesia (magnesite heated to between 700° and 1,000° Celsius to drive off 2 to 10 percent of its carbon dioxide) is mixed with magnesium chloride to create oxychloride (sorel) cement. This cement is used for heavy-duty floorings, stucco, and fireproof building materials. Dolostone, a rock composed chiefly of dolomite, is used as a building stone as well as a refractory material. Magnesium is an essential element in all plants and animals. In green plants, it is a component of chlorophyll; in animals, it plays a role in carbohydrate metabolism and is an important trace element for muscle, nerve tissue, and skeletal structure. Serious dietary deficiencies of magnesium can bring on such symptoms as hyperirritability and soft-tissue calcifica- tion. Karen N. Kähler Further Reading Friedrich, HorstE., andBarry L.Mordike, eds. Magne- sium Technology: Metallurgy, Design Data, Applica- tions. New York: Springer, 2006. Greenwood, N. N., andA. Earnshaw.“Beryllium, Mag- nesium, Calcium, Strontium, Barium, and Ra- dium.” In Chemistry of the Elements. 2d ed. Boston: Butterworth-Heinemann, 1997. Henderson, William. “The Group 2 Elements: Beryl- lium, Magnesium, Calcium, Strontium, Barium, and Radium.”In Main GroupChemistry. Cambridge, England: Royal Society of Chemistry, 2000. Kogel, Jessica Elzea, et al., eds. “Magnesium Minerals and Compounds.” In Industrial Minerals and Rocks: Commodities, Markets, and Uses. 7th ed. Littleton, Colo.: Society for Mining,Metallurgy,and Explora- tion, 2006. Manning, D. A. C. Introduction to Industrial Minerals. New York: Chapman & Hall, 1995. Seelig, Mildred S., and Andrea Rosanoff. The Magne- sium Factor. New York: Avery, 2003. Silva, J. J. R.Fraústo da, and R. J. P. Williams. “The Bio- logical Chemistry of Magnesium: Phosphate Me- tabolism.” In The Biological Chemistry of the Elements: The Inorganic Chemistry of Life. 2d ed. New York: Ox- ford University Press, 2001. Web Sites Natural Resources Canada Canadian Minerals Yearbook, Mineral and Metal Commodity Reviews http://www.nrcan-rncan.gc.ca/mms-smm/busi- indu/cmy-amc/com-eng.htm U.S. Geological Survey Magnesium: Statistics and Information http://minerals.usgs.gov/minerals/pubs/ commodity/magnesium See also: Alloys; Limestone; Metals and metallurgy; Steel. Global Resources Magnesium • 711 Magnetic materials Category: Mineral and other nonliving resources Naturally occurring magnetic materials have been known and used for centuries. Materials that can be temporarily magnetized by an electrical current are widely used in applications ranging from simple electrical appliances and motors to sophisticated computer systems. Definition Substances that respond to a magnetic field are called magnetic materials. The most common magnetic materials are iron (Fe), cobalt (Co), nickel (Ni), and their alloys. These three elements belong to Group VIIIB of the periodic table. Four varieties of magnetism are recognized: ferromagnetism, ferrimagnetism, diamagnetism, and paramagnetism. Iron, cobalt, nickel, gadolinium (Gd), and chromium dioxide (CrO 2 ) are examples of ferromagnetic materials. Ferroferric oxide (Fe 3 O 4 ) is a ferrimagnetic material. Feeble magnetism isexhibited in certain alloys and elements. A substance that is magnetized in the oppo- site direction of the external magnetic field is called a diamagnetic material. Some examples are gold, silver, copper, and quartz. A substance that is magnetized in the same direction as the external magnetic field is called a paramagnetic material. Certain types of spe- cial alloys are paramagnetic. Overview Magnets attract materials or objects made of iron (and steel), cobalt, and nickel. A magnet’s power is strongest atits twoends, called poles. One iscalled the north pole andthe other the southpole. A compass is, in principle, a magnet pivoted at its center which ori- ents itself in the direction of the Earth’s magnetic field. A compasshas long been one ofthe most important navigational instruments onboard ships and air- planes. The largest deposits of the mineral magnetite (Fe 3 O 4 ), magnetic iron ore, are found in northern Sweden. Sizable deposits of magnetite are also found in Australia, Italy, Switzerland, Norway, the Ural Mountains in Russia, and several other regions. In the United States, magnetite is found in Arkansas, New Jersey, and Utah. The Precambrian rocks of the Adirondacks contain large beds of magnetite. The ancient Chinese discovered that a freely sus- pended lodestone (naturally occurring polarized magnetite) would always orient itself in the same geo- graphical direction. This observation led to the development of the compass. In the West, historical rec- ords of magnetic materials date back to the ancient Greeks. By 500 b.c.e., the Greeks had discovered that certain rocks were attracted to iron nails on ships and boats. In 1600, William Gilbert, an English doctor, published De Magnete, in which he identified the Earth itself as a giant magnet. A number of fundamental advances in the practical applications of magnetism occurred in the early nineteenth century. In 1820, the Danish scientist Hans Christian Øersted discovered that a magnetic needle could be deflected by a current in a wire. In 1823, En- glish scientist William Sturgeon wound an insulated copper wire around an iron bar and discovered that the iron bar became a strong magnet. Thusthe electromagnet was born. In 1821, Michael Faradaydem- onstrated the first electricmotor, the “magnetic rotation of a conductor and magnet.” In 1828, Joseph Henry produced silk-covered wires and developed more powerful electromagnets. Magnetic materials have a tremen - dous range of uses, from huge indus - 712 • Magnetic materials Global Resources Magnetite is a type of magnetic material. (USGS) trial electromagnets to the use of “magnetic bubbles” in highlyadvanced computer systems.Magnetic materials are classified into three major categories: hard, soft, and memory-quality materials. Hard magnetic materials have applications as permanent magnets in small motors, small direct-current generators (dyna- mos), measuring instruments, and speaker systems. Soft magneticmaterials—those that are influenced by external fields—are widely used in transformers, generators, motors, and alternators of all sizes and rating capacities. Almost all appliances used in homes and industry, from shavers to washing machines to relays, contain electromagnets with soft magnetic materials. The materials used most often are iron, silicon-iron combinations, nickel-iron alloys, and ferrites. Mem- ory-quality magnetic materials are used to record and store data, either in analog or digital form. Examples are magnetic tapes, drums, and disks. Huge electromagnets are used to move automo- biles or other metal objects in automobile recycling yards and junkyards. Gigantic electromagnets are essential to nuclear fusion experiments. Magnetic- levitation (maglev) trains are held above the ground by superconducting electromagnets. Superconduct- ing electromagnets are also used in magnetic reso- nance imaging(MRI) bodyscanners, devicesthat produce detailed images of the inside of the body and provide diagnostic data to doctors. Mysore Narayanan See also: Cobalt; Iron; Nickel; Steel. Manganese Category: Mineral and other nonliving resources Manganese is one of the most abundant elements in the crust of the Earth and is usually a minor constituent in ordinary rocks. Its chemical and physical properties are similar to those of iron, and the two metals often occur together. Where Found Manganese oxides are abundant in nature; however, large, high-grade deposits are relatively rare. Concen- trations of the element approximately 250 to 500 times greater than the average crustal abundance are required to produce ore. All the major ore deposits are sedimentary in origin and consist of various man - ganese oxide minerals. The major deposits of the world are sedimentary in origin and are located in Russia, Africa, and Brazil. The five leading manganese-producing countries in 2007 were South Africa, Australia, China, Gabon, and Brazil. Together these countries account for 70 percent of the world’s total output. Primary Uses Manganese playsa majorrole insteel production. Sec- ondary uses of this mineral are in alloys, batteries, fertilizers, and the manufacture of chemicals. Technical Definition Manganese (atomic number 25, chemical symbol Mn) is thetwelfth most abundantelement in the crust of the Earth and makes up about 0.1 percent of the crust by weight. In its pure state, which does not occur in nature, it is a hard, brittle metal with a gray color, a melting point of 1,260° Celsius, a boiling point of 1,900° Celsius, and a density of 7.2 grams per cubic centimeter. It resembles iron in many of its properties and has oxidation states of +2, +3, +4, +6, and +7. As is true of iron, the reduced +2 form is quite soluble under near-surface conditions and is carried in solution by stream and groundwater. Description, Distribution, and Forms Because of itsgreat crustal abundance,small amounts of manganese, in the form of dark-colored oxide minerals, are common inmost rocks. Forcommercial production, however, ore bodies averaging at least 35 percent manganese and containing millions of metric tons of the metal are required. The highest-grade ore contains more than 48 percent manganese. Such deposits are not common. All the known major deposits are of sedimentary origin. There are several ore minerals of manganese, but the most important are all oxides: pyrolusite (MnO 2 ), psilomelane (Mn 2 O 3 2H 2 O), and manganite (Mn 2 O 3 H 2 O). Although manganese occurs in several oxidation states, the reduced +2 is most common in subsurface waters because of its solubility. Manganese oxide minerals precipitate readilyat a boundary betweenoxidiz- ing and reducing conditions, such as the reducing groundwater percolating intowell-oxygenated stream water. As a result, manganese oxide coatings on stream pebbles and rocks are common, so common that they usually go unnoticed. Similar black coatings are also Global Resources Manganese • 713 common in arid regions in the form of “desert varnish” and indeep freshwater lakes.In the ocean, large manganese oxide nodules occur. Changes from reducing to oxidizing conditions have been implicated as important in producing all of these common surface forms of manganese oxide, but it is also likely that manganese-oxidizing bacteria play an important role, particularly fordesert varnish andstream pebble coatings. The Challenger expedition in the 1870’s discovered manganese oxide nodules in the deep-ocean basin, but their widespread occurrence and abundance did not become known until sampling in the 1960’s. These nodules are black and rounded to irregular lumps of pebble and cobble size. They exist in all the world’s oceans but are irregularly distributed. The origin of the nodules has been the subject of much research. Evidence indicates that the nodules are continually growing at a very slow rate by the addition of manga - nese and other metals from seawater. The absence of sediment to muddy the water increases their rate of precipitation, a fact which explains why most nodules are found only in the deep-ocean basins, far removed from sediment eroded from landmasses. Manganese is considered to be one of the least toxic of the trace elements. Several thousand parts per million of manganese in the diet of mammals and birds are usually required to develop symptoms of toxicity. The exact amount that is toxic varies from species to species and is also dependent on the form in which manganese isconsumed andthe ageof theindividual. The main symptom reported is a reduced rate of growth because of appetite depression. While very high levels of manganese are required to produce toxic effects from oral consumption, mammals, including humans, appear to have a con- siderably low tolerance to the inhalation of manganese dusts. High levels of such dusts can occur in oc- cupational settings such as steel mills, manganese mines, and certain chemical industries. The lungs ap - parently act as asink from which manganese is contin - ually absorbed.The main toxiceffect produced is a se - 714 • Manganese Global Resources Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.Source: Mineral Commodity Summaries, 2009 2,200,000 1,300,000 2,800,000 1,600,000 940,000 130,000 3,000,000 480,000 1,400,000 Metric Tons Gross Weight 3,500,0003,000,0002,500,0002,000,0001,500,0001,000,000500,000 Ukraine India Gabon China Brazil Australia Mexico South Africa Other countries Manganese: World Production, 2008 rious neurological disease with many symptoms in common with Parkinson’s disease. Such manganese- induced neurotoxicity has been the subject of considerable interest because manganese compounds have been used in gasoline as a replacement for lead compounds. History Manganese oxide has been known since antiquity, when it was used in glass manufacture, but the metal itself was not isolated until 1770. There was little interest in themetal until 1856, whenit was discoveredthat manganese could be used to remove sulfur and oxygen impurities as a slag from molten steel. All steel up to this time had been extremely brittle because of the presence of these impurities. An important world market for manganese quickly developed. The world’smajor deposit of manganesewas discovered in the Nikopol’ Basin in Ukraine in the 1920’s. Subse- quently, this area became the world’s major producer. In the nineteenth century, the United States was self- sufficient in manganese, but these deposits are all ex- hausted. Obtaining Manganese Two types of sedimentary deposits account for most of the world’s production. The first type, illustrated by the world’s largest deposit at Nikopol’ insouthern Ukraine,consists ofman- ganese in the form of earthy masses and nodules of manganese oxide in beds of sandy clay and limestone. This type of deposit is thought to have originated by a two-step process. First, manganese in its reduced form, derived from the weathering and erosion of continental ar- eas, is carried by streams in solution to the open sea. Second, in the sea, reduced manganese undergoes oxidation,causing it toprecip- itate as manganese oxide minerals because of the strongly oxidizing conditions in the open ocean. The second important type of deposit has resulted from the weathering of rocks containing small amounts of manganese silicate and carbonate minerals. These minerals are resistant to weathering, so their relative abundance increases as the less resistant minerals are dissolved. Eventually, a large, high-grade deposit of manganese may be produced. Geologists use the term “residual” to refer to any type of mineral deposit in which the valuable material has been concentrated by weathering. Important manganese deposits of this type occur in Brazil and China. Mining companies became interested in deep-sea manganese nodules in the 1960’s and 1970’s. The richest area seems to be a portion of the deep Pacific floor extending 4,800 kilometers eastward from the southern tip of Hawaii. There are places in this region in which the nodules literallycover the seafloor.Inter- est in the nodules is high because, in addition to averaging 25 percent manganese, they also average about 1.3 percent nickel, 1 percent copper, 0.22 percent cobalt, and 0.05 percent molybdenum, all of which could be recovered as by-products. Between 1962 and 1978 several international consortia spent nearly $100 million studying methods for mining the nodules. At least two promising methods were identified, but no commercial mining of the deep seafloor occurred. Uses of Manganese Most manganese is used during the manufacture of steel to remove sulfur and oxygen. There are no practical replacements for manganese in this essential role. Approximately 90 percent of the manganese Global Resources Manganese • 715 Source: Mineral Commodity Summaries, 2009 Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009. Construction 29% Machinery 10% Transportation 10% Misc. iron and steel uses 51% U.S. End Uses of Manganese that isconsumed eachyear inthe United States is used in the manufacture of steel. Manganese is also used as a component in certain aluminum alloys and in dry cell batteries. Minor amountsare used as a colorant in glass, in fertilizers, and as a gasoline additive. Gene D. Robinson Further Reading Adriano, Domy C. “Manganese.” In Trace Elements in Terrestrial Environments: Biogeochemistry, Bioavailabil- ity, and Risks of Metals. 2d ed. New York: Springer, 2001. Greenwood, N. N., and A. Earnshaw. “Manganese, Technetium, and Rhenium.” In Chemistry of the Elements. 2d ed. Boston: Butterworth-Heinemann, 1997. Howe, P. D., H. H. Malcolm, and S. Dobson. Manga- nese and Its Compounds: Environmental Aspects.Ge- neva, Switzerland: World Health Organization, 2004. Klimis-Tavantzis, Dorothy J., ed. Manganese in Health and Disease. Boca Raton, Fla.: CRC Press, 1994. Kogel, Jessica Elzea, et al., eds. “Manganese.” In Indus- trial Minerals and Rocks: Commodities, Markets, and Uses. 7th ed. Littleton, Colo.: Society for Mining, Metallurgy, and Exploration, 2006. Priest, Tyler. Global Gambits: Big Steel and the U.S. Quest for Manganese. Westport, Conn.: Praeger, 2003. Sigel, Astrid, and Helmut Sigel, eds. Manganese and Its Role inBiological Processes. NewYork: Marcel Dekker, 2000. Wolf, Karl H., ed. Handbook of Strata-Bound and Stratiform Ore Deposits. Vol. 2. New York: Elsevier Sci- entific, 1986. Web Sites Natural Resources Canada Canadian Minerals Yearbook, Mineral and Metal Commodity Reviews http://www.nrcan-rncan.gc.ca/mms-smm/busi- indu/cmy-amc/com-eng.htm U.S. Geological Survey Manganese: Statistics and Information http://minerals.usgs.gov/minerals/pubs/ commodity/manganese See also: Bessemer process; Clean Air Act; Food chain; Iron; Marine mining; Sedimentary processes, rocks, and mineral deposits; Steel. Manhattan Project Category: Historical events and movements The Manhattan Engineer District was created in Au- gust, 1942, to sponsor the Manhattan Project, a top- secret effort to produce the atomic bomb in time to be used during World War II. The Manhattan Project’s legacy, in addition to the destruction wrought by the two atomic bombs the United States dropped on Japan, includes the proliferation of nuclear weapons and the peacetime development of nuclear power plants. Background During World War II, the United States, Germany, Great Britain, the Soviet Union, France, and Japan all had projects toexamine the feasibility ofconstructing an atomic bomb. Japanese progress was minimal, and French progress halted with the German occupation of France. American efforts were spurred on by the British and by scientists such as Leo Szilard, Eugene Paul Wigner, and Enrico Fermi, who fled oppression in Europe. Since the Germans had a considerable head start in addition to formidable industrial and scientific resources, many feared that Adolf Hitler would develop the atomic bomb first. Developing and Constructing the Bomb Enough work had been done prior to the Manhattan Project to convince those involved that the problems of producing a bomb could probably be surmounted if sufficient resourceswere made available.Because of the war mobilization, the Army Corps of Engineers was managing construction contracts amounting to $600 million a month, and funds for the top-secret Manhattan Project were hidden within that amount. The initial cost estimate for the project was $133 million; the actual cost was about $2 billion. Before the Manhattan Project, American atomic bomb research was conducted by various scientists at several universities. Progress was intermittent. On September 17, 1942, Colonel (soon to be General) Leslie Richard Groves was appointed to head the Manhattan EngineerDistrict. Groves wasan engineer, and his supervision of the building of the Pentagon had demonstrated a knack for untangling bureau- cratic messes. He was regarded as arrogant and abrupt but alsoas aperson whocould getthe jobdone right. Under Groves, the Manhattan Project proceeded 716 • Manhattan Project Global Resources at breakneck speed. Factories were built before the machines they would house were fully worked out, and full-scale machines were built before prototypes were fully tested. While this approach did not always work, it worked well enough. At Hanford, Washing- ton, fifty thousand construction workers built three large nuclear reactors to produce plutonium along with three separation plants to remove the plutonium from the used reactor fuel. A huge gaseous diffusion plant and an electromagnet separation plant were built at Oak Ridge, Tennessee, to separate uranium 235 from the more common uranium 238. Because of a copper shortage, more than 12,000 metric tons of silver were borrowed from the federal treasury and made into conductors for the electromagnets. The design and construction of the bombs were done at the Los Alamosweapons laboratory,headed by J. Rob - ert Oppenheimer. At the project’s peak, more than 160,000 workers were employed at twenty-five sites. Most of the Manhattan Project workers knew only that they were working on something very important and that it might help end the war. Many of those who knew that they were working on the atomic bomb hoped that it would help end the war and that it might make future wars unthinkable. Charles W. Rogers See also: Isotopes, radioactive; Nuclear energy; Nu- clear waste and its disposal; Plutonium; Uranium. Manufacturing, energy use in Category: Obtaining and using resources Industrial processes consume roughly 46 percent of world energy each year. In the United States, about 80 percent of that energy goes to the basic production industries of iron, steel, aluminum, paper, chemicals, and nonmetallic minerals (cement, brick, glass, and ceramics). Background The sophistication of a society’s technology can be judged by what it can make and how efficiently it can make those items. In ancient civilizations, rock and wood yieldedto metal,fired pottery, andglass. Bronze and brass weapons swept aside stone. Then iron and steel replaced the softer metals. Muscle power was sporadically aidedby water power in antiquity, but the intensive use of water power began in Europe in the Middle Ages. Besides grinding flour, water mills supplied power for large-scale weav- ing, for sawmills, and for blowing air onto hot metal and hammering the finished metals. The gearing required to modify the motion and move it throughout a workshop also applied to wind power, and Dutch mills led manufacturing in the late Middle Ages. A series of inventions led to James Watt’s improved steam engine in 1782. The immediate goal was pump- ing water out of coal mines, but steam engines also allowed factory power to be located anywhere. Steam- powered locomotives allowed materials to be more easily moved to those locations. At the beginning of the twentieth century, small electric motors allowed a further decentralization of industry. A small shop required only a power cable, Global Resources Manufacturing, energy use in • 717 Robert Oppenheimer, the scientific director of theManhattan Project and architect of the atomic bomb, left, speaks with General Leslie Groves, the military director of the Manhattan Project, in Alamo- gordo, New Mexico. (Popperfoto/Getty Images) . considered to be one of the least toxic of the trace elements. Several thousand parts per million of manganese in the diet of mammals and birds are usually required to develop symptoms of toxicity. The. boiling point of 1,900° Celsius, and a density of 7.2 grams per cubic centimeter. It resembles iron in many of its properties and has oxidation states of +2, +3, +4, +6, and +7. As is true of iron,. Magnesium Global Resources Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.Source: Mineral Commodity Summaries, 2009 U.S. data were withheld to avoid disclosure of company