topaz, (9) corundum, and (10) diamond. Minerals can scratch other minerals of the same or lesser hardness. The hardness of minerals can be tested using common materials, including the fingernail (a little over 2), cop- per (about 3), a steel nail or pocket knife (a little over 5), a piece of glass (about 5.5), and a steel file (6.5). Color Although color is a prominent feature of minerals, it is not a reliable indicator for identifying minerals. The color of some minerals is the result of major elements in their chemical formula, such as the blue color of az- urite and the green color of malachite (copper), the pink color of rhodonite and rhodochrosite (manga- nese), and the yellow color of sulfur. Many minerals come in a variety of colors. Quartz is colorless and transparent whenpure,butitmay alsobewhite (milky quartz), pink (rose quartz), purple (amethyst), yellow (citrine), brown (smoky quartz), or other colors. Sim- ilarly, feldspar and fluorite come in many hues. Color may be caused by impurities, such as iron (pink, green, or greenish yellow), titanium (pink or blue), chromium (red or green), vanadium (green), and nickel (yellow). Milky quartz is white because it con- tains tiny fluidinclusions.Coloration can be the result of defects in the crystal structure; for example, the purple of amethyst and fluorite and the brown of smoky quartz. Unusual colors may also be induced in minerals by exposing them to radiation, which dam- ages the crystal structure (such as black quartz). Luster Luster refers to the “shine,” or quality of reflectivity of light from the mineral’s surface. Minerals can be divided into two luster groups: metallic luster and non- metallic luster. Metallic minerals include econom- ically valuable metals such as gold, silver, and na- tive copper, and some metal sulfides such as pyrite (FeS 2 or iron sulfide) and galena (PbS or lead sul- fide). Nonmetallic minerals include those with vitre- ous or glassy luster (quartz), earthy or dull luster (kaolinite andotherclays), pearly (talc),silky(fibrous minerals such as gypsum, malachite, and chrysotile asbestos), greasy (nepheline), resinous (resembling resin or amber, such as sulfur), and adamantine or brilliant (diamond). Streak Streak refers to the color of the mineral in powdered form, viewed after the mineral is rubbed on an un - glazed porcelain tile or streak plate. Streak color is more diagnostic than mineral color because it is con- stant for a particular mineral. A mineral may come in several colors, but its streak is the same color for all. Streak color is not always what one might pre- dict from examining the mineral; a sparkling silver- colored mineral, specular hematite, has a red-brown streak, and pyrite, a golden metallic mineral, has a dark gray streak. Not all minerals have a streak. The streak plate has a hardness of about 7 on the Mohs hardness scale. Minerals harder than this will not leave a streak, but their powdered colors can be stud- ied by crushing a small piece. Cleavage Cleavage is one of the most diagnostic physical prop- erties of minerals. Cleavage refers to the tendency of some minerals to break along smooth, flat planes that are related to zones of weak bonding between at- oms in the crystal structure. Some minerals, however, have no planes of weakness in their crystal structure and therefore lack cleavage. Cleavage is discussed by referring to the number of different sets of planes of breakage and the angles between them. Minerals that have a prominent flat, sheetlike cleavage (such as the micas, muscovite and biotite) have one direction of cleavage, orperfect basal cleavage. Thissheetlike cleav- age makes muscovite economically valuable; it was once used in window-making material and is still used in some stove windows and in electrical insulation. Feldspar and pyroxene have two directions of cleav- age at right angles to each other, and the amphiboles (hornblende and others) have two directions of cleav- age at approximately 60° and 120° to each other. Other minerals have three directions of cleavage. Ha- lite (table salt) and galena have cubic cleavage (three directions of cleavage at right angles to one another) and break into cubes. Calcite has rhombohedral cleav- age (three directions of cleavage not at right angles; the angle is about 74 degrees) and breaks into rhom- bohedrons. Fluorite has four directions of cleavage and breaks into octahedrons with triangular faces. Sphalerite has six directions of cleavage. Fracture Irregularbreakage in mineralswithoutplanes of weak bonding is fracture. There are several types of frac- ture. Many minerals have uneven or irregular frac - ture. Conchoidal fracture is characterized by smooth, curved breakage surfaces, commonly marked by fine 758 • Minerals, structure and physical properties of Global Resources parallel linesresembling thesurfaceof ashell (seen in quartz, obsidian, and glass). Rocks and minerals with conchoidal fracture were used by American Indians for arrowheads. Hackly fracture is jagged with sharp edges and is characteristic of metals such as copper. Fibrous or splintery fracture occurs in asbestos and sometimes gypsum. Earthy fracture occurs in clay minerals such as kaolinite. Density and Specific Gravity Density is defined as mass per unit volume, or how heavy a material is for its size. Specific gravity (or rela- tive density) is commonly used when referring to min- erals. Specific gravity expresses the ratio between the weight of a mineral andtheweightof an equal volume of water at 4° Celsius. The terms density and specific gravity are sometimes used interchangeably, but den- sity requires the inclusion of units of measure, whereas specific gravity is unitless. Quartz has a spe- cific gravity of 2.65. Barite has a specific gravity of 4.5 (heavy for a nonmetallic mineral), which makes it economically valuable for use in oil and gas well drill- ing. Metals have higher specific gravity than nonmet- als, for example, galena (7.4 to 7.6), and gold (15.0 to 19.3). The high specific gravity of gold allows it to be separated from less dense minerals by panning. Tenacity, Taste, and Magnetism Tenacity is the resistance of a mineral to bending, breaking, crushing, or tearing. Minerals may be brit- tle (break or powder easily), malleable (can be ham- mered into thin sheets), ductile (can be drawn into a thin wire), sectile (can be cut into thin slivers with a knife), elastic (bend but return to their original form), or flexible (bend and stay bent). Metallic min- erals are commonly malleable and ductile (gold, cop- per). Copper is used for electrical wire because of its ductility. Some minerals can be identified by taste. Taste is a property of halite (NaCl), used as table salt. Sylvite (KCl, or potassium chloride) has a bitter salty taste and is used as a salt substitute for people with high blood pressure because it does not contain sodium. Magnetism is a property that causes certain miner- als to be attracted to a magnet. Magnetite (Fe 3 O 4 ) and pyrrhotite (Fe 1−x S) are the only common magnetic minerals. Lodestone, a variety of magnetite, acts as a natural magnet. In the presence of a powerful mag - netic field, some other iron-bearing minerals become magnetic (garnet, biotite, and tourmaline), whereas other minerals are repelled by the magnet (gypsum, halite, and quartz). Electromagnetic separators are used to separate minerals with different magnetic sus- ceptibilities. Electrical Properties Some minerals have electrical properties. Piezoelec- tricity occurs when pressure is exerted in a particular direction in a mineral (along its polar axis), causing a flow of electrons or electrical current. Piezoelectric- ity was first detected in quartz in 1881, and it has since been used in a number of applications ranging from submarine detection to keeping time (in quartz watches). When subjected to an alternating electrical current, quartz is mechanically deformed and vibrates; radio frequencies are controlled by the frequency of vibration of the quartz. Pyroelectricity is caused when temperature changes in amineralcreate uneven thermal expansionandde- formation. Tourmaline and quartz are pyroelectric. Luminescence Luminescence is emission of light from a mineral. Minerals that luminesce or glow during exposure to ultraviolet light, X rays, or cathode rays are fluores- cent. If the luminescence continues after the radia- tion source is turned off, the mineral is phosphores- cent. The glow results from impurities in the mineral absorbing invisible, short wavelength radiation and then reemitting radiation at longer wavelengths (visi- ble light). Minerals vary in their ability to absorb dif- ferent wavelengths of ultraviolet (UV) light. Some fluoresce only in short wavelength UV, some fluo- resce only in long wavelength UV, and some fluores- cein both types. Fluorescence is unpredictable; not all minerals of a given type fluoresce. Minerals that com- monly fluoresce include fluorite, calcite, diamond, scheelite, willemite, hyalite, autunite, and scapolite. Fluorescence has some practical applications in pros- pecting and mining. Synthetic phosphorescent mate- rials have also been developed for commercial uses. Some minerals emit light when heated. This prop- erty is called thermoluminescence. Thermolumi- nescent minerals include fluorite, calcite, apatite, scapolite, lepidolite, and feldspar. Minerals that lumi- nesce when crushed, scratched, or rubbed are tribo- luminescent. This is a property of fluorite, sphalerite, and lepidolite, and less commonly of pectolite, am - blygonite, feldspar, and calcite. Global Resources Minerals, structure and physical properties of • 759 Reaction to Hydrochloric Acid Calcite (CaCO 3 ) and other carbonate minerals effer- vesce or fizz in hydrochloric acid, but some will not react unless the acid is heated or the mineral is pow- dered. Bubbles of carbon dioxide (CO 2 ) gas are re- leased, and the reaction proceeds as follows: CaCO 3 + 2 HCI → CaCl 2 + H 2 O + CO 2 (gas) Radioactivity Radioactive minerals contain unstable elements that alter spontaneously to other kinds of elements, releas- ing subatomic particles and energy. Radioactivity can be detected using Geiger-Müller counters, ionization chambers, scintillometers, and similar instruments. Some elements have several different isotopes, differ- ing by the number of neutrons in the nucleus. Radio- active isotopes include uranium 235 (U 235 ), uranium 238 (U 238 ), and thorium 232 (Th 232 ). Uranium 235 is the primary fuel for nuclear power plants. Radioac- tive minerals include uraninite (pitchblende), car- notite, uranophane, and thorianite. Radioactive min- erals occur in granites and granite pegmatites, in sandstones, and in black organic-rich shales, and are used for nuclear energy, atomic bombs, coloring glass and porcelain; in photography; and as a chemical re- agent. Radioactivity is also used in radiometric dating to determine the ages of rocks and minerals. Classification of Minerals Minerals have been classified or grouped in several ways, but classification based on chemical composition is the most widely used. Minerals are grouped into the following twelve categories on the basis of their chemi- cal formulas: native elements, oxides and hydroxides, sulfides, sulfosalts, sulfates, halides, carbonates, ni- trates, borates, phosphates, tungstates, and silicates. Native Elements Native elements are minerals composed of a single el- ement that is not combined with other elements. About twenty native elements occur (not including at- mospheric gases), and they are divided into metals, semimetals, and nonmetals. The native metals in- clude gold (Au), silver (Ag), copper (Cu), iron (Fe), platinum (Pt), and others. They share the physical properties of malleability, hackly fracture, and high specific gravity, along with metallicluster. Theiratoms are heldtogether by weak metallicbonds.They are ex - cellent conductors of heat and electricity and have fairly low melting points. The native semimetals in - clude arsenic (As), bismuth (Bi), antimony (Sb), tel- lurium (Te), and selenium (Se). They are brittle and much poorerconductorsofheat. These properties re- sult from bonding intermediate between true metal- lic and covalent. The native nonmetals include sulfur (S) and two forms of carbon (C), diamond and graph- ite. These minerals have little in common, but they are distinctive and easily identified. Diamond and graph- ite are polymorphs, a term meaning “many forms.” Their chemical composition is identical, but they have different crystalstructures. Diamond has a tight, strongly bonded structure, whereas graphite has a loose, open structure consisting of sheets of atoms. Oxides and Hydroxides Chemically, the oxide and hydroxide minerals consist of metal ions (of either one or two types of metals) combined with oxygen in various ratios, such as Al 2 O 3 (corundum) or MgAl 2 O 4 (spinel), or metals com- bined with oxygen and hydrogen, such as Mg(OH) 2 (brucite) or HFeO 2 (goethite). The oxides and hy- droxides are a diverse group with few properties in common. Several minerals of great economic impor- tance occur in this group, including the chief ores of iron (magnetite, Fe 3 O 4 , and hematite, Fe 2 O 3 ), chro- mium (chromite), manganese (pyrolusite, manga- nite, psilomelane), tin (cassiterite), and aluminum (bauxite). Some minerals in this group form from molten rock or hydrothermal (hot water) solutions, but others form on or near the surface of the Earth as a result of weathering and may contain water. Sulfides Chemically, the sulfides consist of a metal ion com- bined with sulfur. They are an economically impor- tant classofminerals that includes numerous oremin- erals. Many of the sulfides are metallic, with high specific gravity, and most are fairly soft. They tend to be brittle, and they have distinctive streak colors. Many sulfides have ionic bonding, but others have metallic bonding, at least in part. Sphalerite has cova- lent bonding. Among the sulfides are ores of lead (galena, PbS), zinc (sphalerite, ZnS), copper (chalcocite, Cu 2 S; bornite, Cu 5 FeS 4 ; and chalcopyrite, CuFeS 2 ), silver (argentite, Ag 2 S), mercury (cinnabar, HgS), and mo - lybdenum (molybdenite, MoS 2 ), as well as pyrite (FeS 2 ), used to manufacture sulfuric acid. 760 • Minerals, structure and physical properties of Global Resources Sulfosalts The sulfosalts are a type of unoxidized sulfur mineral. They consist of a metal and a semimetal combined with sulfur. There are nearly one hundred sulfosalts, including arsenopyrite (FeAsS), tetrahedrite (Cu 12 Sb 4 S 13 ), and pyrargyrite (Ag 3 SbS 2 ). Some are useful as ore minerals. Sulfates The sulfates consist of metal plus a sulfate (SO 4 ) group. The sulfates are typically soft, and some are translucent or transparent. They include both anhy- drous (without water) and hydrous (water-bearing) sulfate minerals. Anhydrous sulfates include barite (BaSO 4 ), anhydrite (CaSO 4 ), celestite (SrSO 4 ), and anglesite (PbSO 4 ). The hydrous sulfates include gyp- sum (CaSO 4 C 2H 2 O) and epsomite (MgSO 4 C 7H 2 O). The structure of gypsum consists of sheets or layers of calcium and sulfate ions separated by water mole- cules. Loss of water molecules causes the structure of the mineral tocollapseinto anhydrite, with a decrease in volume and loss ofcleavage.Themost common sul- fate, gypsum is used in the production of plaster of paris, drywall, soil conditioner, andportland cement. Halides The halides contain negatively charged halogen ions (chlorine, fluorine, bromine, and iodine), bonded ionically to positively charged ions (such as sodium, potassium, calcium, mercury, and silver). Many have symmetrical crystalstructures resulting in cubic cleav- age (halite, NaCl, and sylvite, KCl) or octahedral cleavage (fluorite, CaF 2 ). Many of the halides are water-soluble salts (such as halite and sylvite), and may form from the evaporation of water. Many are transparent or translucent. All are fairly soft and are light in color when fresh. Some of the silver and mer- cury halides will darken in color on exposure to light, hence their use in photography. Carbonates Carbonate mineralscontainthe carbonate ion, CO 3 2− . Carbonate minerals are readily identified by their ef- fervescence in hydrochloric acid, although for some carbonates, the acid must be hot or the mineral must be powdered to obtain the reaction. Some carbonates (such as cerussite, PbCO 3 ) react to nitric acid. Car - bonates include calcite and aragonite (CaCO 3 ), dolo - mite (CaMg(CO 3 ) 2 ), magnesite (MgCO 3 ), and sider - ite (FeCO 3 ). The colorful malachite (green), azurite (blue), and rhodochrosite (pink) are also carbonates. Most carbonates are fairly soft, and rhombohedral cleavage is common. Nitrates The nitrate minerals contain the nitrate ion, NO 3 − . Most nitrates are water soluble and are fairly soft. They are light in color, and some are transparent. The nitrates include soda niter (NaNO 3 ), which is found in desert regions and used in explosives and fertilizer, and niter or saltpeter (KNO 3 ), which forms as a coat- ing on the walls of caves and is used as a fertilizer. Borates The boratescontainboron bonded tooxygenand asso- ciated with sodium or calcium, with or without water. Some borates form in igneous deposits, but most are found indry lake bedsin arid areas.Amongthe borates are borax, kernite, and ulexite. Boraxisusedfor wash- ing, as an antiseptic and preservative, in medicine, and in industrial and laboratory applications. Phosphates The phosphate minerals contain the PO 4 3− group, bonded to positively charged ions such as calcium, lithium, iron, manganese, lead, and iron, with or with- out water. Apatite (Ca 5 (F,Cl,OH)(PO 4 ) 3 ) is the most important and abundant phosphate mineral. It is the primary constituent of bone and is used for fertilizer. Turquoise is a phosphate mineral. Tungstates The tungstates contain tungsten (chemical symbol W). Tungstates form a small group of minerals that in- clude wolframite and scheelite (which is fluorescent); both are ores of tungsten. Silicates The silicates are the largest group of minerals, and they include the major rock-forming minerals of the Earth’s crust, feldspar and quartz, as well as olivine, pyroxene, amphibole, and the micas. Most are fairly hard, with glassy luster and low to moderate specific gravity; they crush to a light-colored powder. Silicates consist of silicon and oxygen, generally accompanied by other ions such as aluminum, potassium, calcium, sodium, iron, and magnesium. Silicate structure is based on the silicate tetrahedron, which consists of four oxygenatomsarranged aroundonesilicon atom. Global Resources Minerals, structure and physical properties of • 761 These tetrahedra are arranged in several characteris - tic patterns that allow the silicates to be classified into a number of groups, including isolated tetrahedra (neosilicates), pairs of tetrahedra (sorosilicates), rings of tetrahedra (cyclosilicates), single and double chains of tetrahedra (inosilicates), sheets of tetrahedra (phyl- losilicates), and three dimensional frameworks of sili- cate tetrahedra (tectosilicates). Neosilicates tend to be compact and hard, with fairly high specific gravity. Olivine, garnet, zircon, to- paz, staurolite, and kyanite are neosilicates. Sorosili- cates (or “sister” silicates) include the minerals epi- dote, prehnite, and hemimorphite. Cyclosilicates are characterized by prismatic, trigonal, tetrahedral, or hexagonal habits. Beryl has rings of six silicate tetra- hedra, reflected in its hexagonal (six-sided) crystals. Tourmaline and chrysocolla are also in this group. Inosilicates (single-chain and double-chain sili- cates) tend to be fibrous or elongated, with two direc- tions of cleavage parallel to the elongation. They in- clude pyroxenes (including hypersthene, augite, and diopside), pyroxenoids (including wollastonite), and amphiboles (hornblende, tremolite, actinolite, and others). Phyllosilicates, or sheet silicates, have one promi- nent direction of cleavage and tend to have a platey or flaky appearance. They are generally soft, have low specific gravity, and may have flexible or elastic sheets. The micas (muscovite, biotite, lepidolite, and phlogopite), and the clay minerals (kaolinite, illite) belong to this group, as do talc, serpentine, chlorite, and others. The earth’s crust is dominated by tectosilicates, or framework silicates. This is the group that contains feldspar and quartz, the two most abundant minerals in the Earth’s crust. Quartz is chemically the simplest silicate, with the chemical formula SiO 2 . Feldspar is a group of minerals, including orthoclase and micro- cline (two different crystal structures with the for- mula KAlSi 3 O 8 ) and plagioclase (a solid solution se- ries which ranges in composition from NaAlSi 3 O 8 to CaAl 2 Si 2 O 8 ). Tectosilicates tend to be of low density and compact habit. Feldspathoids (including nephel- ine and sodalite) and zeolites (analcime and others) are also in this group. Pamela J. W. Gore Further Reading Bishop, A. C., A. R. Woolley,andW. R. Hamilton. Cam - bridge Guide to Minerals, Rocks, and Fossils. Rev. and expanded ed. New York: Cambridge University Press, 1999. Chesterman, Charles W. National Audubon Society Field Guide to North American Rocks and Minerals. Edited by Kurt E.Lowe. New York:Alfred A.Knopf, 1995. Klein, Cornelis, and Barbara Dutrow. The Twenty-third Edition of the Manual of Mineral Science. 23d ed. Hoboken, N.J.: J. Wiley, 2008. Mottana, Annibale, Rodolfo Crespi, and Giuseppe Liborio. Simon and Schuster’s Guide to Rocks and Min- erals. Translated by Catherine Athill, Hugh Young, and Simon Pleasance, edited by Martin Prinz, George Harlow, and Joseph Peters. New York: Si- mon and Schuster, 1978. Nesse, William D. Introduction to Mineralogy. New York: Oxford University Press, 2000. Perkins, Dexter. Mineralogy. 2d ed. Upper Saddle River, N.J.: Prentice Hall, 2002. Pough, Frederick H. A Field Guide to Rocks and Min- erals. 5th ed. Photographs by Jeffrey Scovil. Boston: Houghton Mifflin, 1996. Wenk, Hans-Rudolf, and Andrei Bulakh. Minerals: Their Constitution and Origin. New York: Cambridge University Press, 2004. Zim, Herbert S., and Paul R. Shaffer. Rocks, Gems, and Minerals: A Guide to Familiar Minerals, Gems, Ores, and Rocks. Rev. and updated ed. Revised by Jona- than P. Latimer et al., illustrated by Raymond Perlman. New York: St. Martin’s Press, 2001. Web Site Joseph R. Smyth, University of Colorado at Boulder Mineral Structure Data http://ruby.colorado.edu/~smyth/min/ minerals.html See also: Crystals; Gems; Isotopes, radioactive; Mohs hardness scale; Native elements; Silicates; Silicon. Minerals Management Service Category: Organizations, agencies, and programs Date: Established 1982 The Minerals Management Service is the agency within the U.S.Department of the Interiorthatcollects, accounts for, and distributes revenues from mineral 762 • Minerals Management Service Global Resources production on federal and American Indian lands. It also manages the mineral resources and the natural gas and oil leasing programs for federal lands that ex- ist below sea level on the continental shelf. Background The Minerals Management Service (MMS) was estab- lished in1982on the recommendationofthe Indepen- dent Commission on Fiscal Accountability. The MMS formed the Royalty Management Program to account for revenues related to mineral production on all fed- eral lands and American Indian reservations and the Offshore Minerals Management Program to account for revenues generated on the outer continental shelf. The outer continental shelf includes submerged lands that lie between individualstates’seaward jurisdiction and the seaward extent of federal jurisdiction. The MMS also seeks to ensure that exploration and produc- tion of the U.S. offshore natural gas, oil, and mineral resourcesisdone in anenvironmentally safe manner. Impact on Resource Use The day-to-day management of oil and gas develop- ment and leasing programs on the federal outer con- tinental shelf is supervised by three regional offices located in New Orleans, Louisiana; Camarillo, Cali- fornia; and Anchorage, Alaska. The MMS headquar- ters, located in Washington, D.C., is responsible for providing national policy guidelines and regulations for offshore leasing programs, conducting resource and environmental safety assessments, and directing international marine minerals programs. The establishment of the MMS increased govern- ment efficiency in minerals management. The Roy- alty Management Programdesigneda centralized, au- tomated fiscal and production accounting systemthat increased timely revenue disbursement from 92 per- cent to 99 percent. The Offshore Minerals Manage- ment Program has increased the number of leases, the number of hectares leased, and the volume of gas and oil production that it oversees. It has also in- creased the number of pipeline kilometers available to the producers. The MMS has conducted studies on the continental shelf of the United States to support risk assessment analysis regarding oil spills and to pro- vide safer transport of potential pollutants on the ocean. Ocean circulation studies have been conducted in order to plan safer routes and reduce oil spills. The MMS has also significantly reduced the rate of oil spills since its inception. The MMS has performed air quality studies in the northern Gulf of Mexico to assess the effect of emis- sions on air pollutants generated on the outer conti- nental shelf as a result of offshore natural gas and oil development activities near the states of Texas and Louisiana. Research has also been done on the long- term, chronic, sublethal impacts to marine life from offshore gas and oil discharges. The MMS monitors the distribution, behavior, habitats, and migrations of bowhead whales and other marine mammals and sea turtles to ensure that they are not adversely affected by the oil and gas industry. The MMS studies the ef- fects on the environment and the social and eco- nomic benefits and costs to communities before mak- ing decisions regarding leasing arrangements, pipeline routings, and landfalls. Dion C. Stewart Web Site Minerals Management Service http://www.mms.gov/ See also: Coastal Zone Management Act; Council of Energy Resource Tribes; Department of the Interior, U.S.; Exclusive economic zones; Law of the sea; Ma- rine mining; Oil spills; Public lands. Mining. See Open-pit mining; Quarrying; Strip mining; Underground mining Mining safety and health issues Category: Social, economic, and political issues Mining is an inherently hazardous industry. Signifi- cant reforms and improvements were madeinthe twen- tieth century to address the health and safety hazards faced by miners, often in response to major disasters that heightened public awareness of these problems. Background Mining is one of the most hazardous of major indus- tries. Miners, particularly in underground opera - tions, face a wide range of safety and health hazards, from immediate threats such as fire or explosion to Global Resources Mining safety and health issues • 763 the risk of developing lung disease or other illnesses from years of exposure to adverse conditions. Most of the effort to address mining safety and health came in the twentieth century, with labor organizations, min- ing management, and government working (both separately and collectively) toward reform. Increased worker and management awareness as well as the ef- forts of regulatory agencies have led to a decrease in industry-related injury andillness.However,while the industrialized nations have made considerable prog- ress in mining safety and health, technological and la- bor standards vary greatly throughout the world. Safety Hazards One of the greatest safety hazards facing underground miners is that of fire and explosion. Workers can be trapped underground and asphyxiated, or crushed as mine structures collapse. Many gases found in mines have explosive properties. Firedamp, a highly flam- mable gaseous mixture composed mainly of meth- ane, is common in coal and lignite mines and is some- times found in potassium mines and bituminous shales. It is explosive in concentrations of 5 to 15 per- cent in air. In some coal mines, huge amounts of car- bon dioxide may be released from the exposed coal with explosive force. Increasing ventilation or the draining off of flammable and explosive gases can di- lute their concentrations to safe levels. Controlling outside ignition sources, such as electrical equipment that could spark or heat excessively, is another way to reduce the risk of fire and explosion. Airborne dust is also capable of igniting and ex- ploding. Drilling, cutting, and breaking rock with compressed-air equipment generates airborne rock dust. Drills and other equipment with an internal water feed that sprays rock surfaces during operation help to reduce dust concentrations. Exhaust ventila- tion and dust collection systems also reduce the dust- ignition hazard. Other safety hazards that miners face include cave- ins, flooding, falling rocks and other objects, slipping and falling, handling of explosives, and working with and around heavy machinery and vehicles. While some accidents and injuries are inevitable, many can be reduced or eliminated through worker training and safe work practices. Health Hazards As noted above,miningequipment generates airborne dust. Dust particles measuring 0.5 to 5 micrometers in diameter are especially dangerous, as they can settle in the lungs. Prolonged inhalation of metallic or min- eral dusts can lead to a lung disease called pneumoco- niosis. Black lung disease is a well-publicized form of pneumoconiosis brought on by coal dust. The effects of asbestos exposure are also widely known: Inhaling particles of this fibrous mineral can cause asbestosis, a chronic lunginflammation,and lung cancer. Workers in quarries and limestone mines can develop silicosis, a fibrous lung disease caused by inhaling silica dust. Dust control measures and respiratory protection equipment are crucial to miner health. 764 • Mining safety and health issues Global Resources Injuries, Fatalities, and Citations in U.S. Mines, 2000-2007 All Mines Coal Metal and Nonmetal 2000 2006 2007 2000 2006 2007 2000 2006 2007 Fatalities 85 73 64 38 47 33 47 26 31 Fatal injury rate 0.03 0.02 0.02 0.04 0.40 0.29 0.02 0.01 0.01 All injury rate 5.13 3.64 3.42 6.64 4.46 4.19 4.45 3.19 3.01 Citations and orders 120,269 140,268 145,050 58,394 77,732 84,722 61,875 62,536 60,328 Percentage of citations that are S&S 36 33 31 42 40 38 31 24 23 Source: U.S. Mine Safety and Health Administration, Office of Program Education and Outreach Services, “Mine Safety and Health at a Glance,” February, 2008. Note: S&S citations are given for violations deemed to contribute “significantly and substantially” to mining hazards. Gases and vapors pose another inhalation hazard for miners. Certain ores—notably those of arsenic, manganese, mercury, and sulfur—-can emit toxic fumes. Hydrogen sulfide, a gas produced by the de- composition of pyrites by water, is poisonous and kills quickly. Radium and uranium disintegrate to form ra- don gas, which can cause lung cancer when inhaled. Other gases, such as methane, can cause asphyxia- tion. Ventilation systems, air monitoring, and respira- tory protective equipment all contribute to worker safety where inhalation hazards are present. Another common problem in mines is extreme heat, the result of the increase of temperature with depth (the geothermal gradient) coupled with the heat generated by mining equipment. Many mines are also naturally damp, a problem compounded by water sprays used fordustsuppression. High humidity interferes with the evaporation of sweat and hence with the body’s natural cooling ability. The warm, damp environment not only leads to heat-related ill- nesses such as heatstroke but also is con- ducive to parasite infestation. Overly hot conditions can be eased through good ventilation systems,climatecontrol, cloth- ing cooled by dry ice, and limited work times. History The importance ofthe physical well-being of miners has been recognized for centu- ries. Georgius Agricola, the sixteenth cen- tury German scientist known as the father of mineralogy, writes of the hazardous conditions in mines of his day.In addition to the health and safety hazards noted above, early miners (particularly pros- pectors in the American West during the 1800’s) contended with food shortages, vermin, cold, epidemics, and general poor health brought on by poor sanita- tion and a lack of proper medical atten- tion for injuries and illnesses. Early safety measuresemployedat min- ing operations included the drilling of ventilation tunnels to provide fresh air at depth; the use of canaries or dogs to test for carbon monoxide; the introduction of the Davy safety lamp for use in coal mines in 1815; and the introduction of ventilation blowers in 1865. The first officially recorded mining disaster in the United States was an explosion at the Black Heath Coal MinenearRichmond, Virginia, in 1839,inwhich 52 men died. In 1869, there were two major coal-mine disasters: a fire at the Yellowjacket Mine that claimed 49 miners’ lives, and another at the Avondale Mine in Plymouth, Pennsylvania, in which 179 miners died. Subsequent legislation was passed that required two exits at every mine and prohibited the placement of ore-breaking equipment over the shaft. There were several large coal-mining disasters in the United States in the early twentieth century. In 1900, an explosion at the Scofield Mine in Scofield, Utah, killed 200 miners. In 1907, another 361 died in an explosionandfire at Monongah,West Virginia, the worst mining disaster in the history of the United States. Two weeks later, 239 miners were killed at Jacobs Creek, Pennsylvania. In 1908, at Marianna, Pennsylvania, 154 miners were killed. Another 259 died in 1909 in a fire at Cherry, Illinois. Global Resources Mining safety and health issues • 765 The implements of mining safety have evolved greatly inthe one hundred years since this photograph was taken. The miner is wearing a Draeger oxygen helmet. (The Granger Collection, New York) This series of disasters led Congress to pass the Or - ganic Act of 1910, which established the U.S. Bureau of Mines (USBM) under the Department of the Inte- rior. The idea of such a bureau, which would oversee the collection, evaluation, and dissemination of scien- tific, technical,andeconomic data ofvalueto the min- eral industries, had been under consideration for a number of years. The early USBM focused on reduc- ing the mortality rate of miners; to this end, it investi- gated mine explosions, promoted miner safety and accident prevention through training, and strove to- ward improvement of working conditions for miners. However, the Organic Act did not permit the USBM to inspect mines, and adoption of its technical recom- mendations was entirely voluntary. In 1915, Congress passed an act that authorized the establishment of seven mine-safety stations. While the USBM’s early research helped to reduce the rate of mining-related fatalities, disasters contin- ued to claim miners’ lives. From about 1910 until about 1940, miners died in work-related accidents at an average rate of 2,000 per year. The death of 276 miners in a 1940 coal mine disaster led to passage of the Coal Mine Inspection and Investigation Act of 1941, which authorized the USBM to enter and in- spect mines and recommend corrective action. Coal mine explosions killed 111 miners at the Cen- tralia Number 5 Mine in southern Illinois in 1947 and 119 miners at the Orient Number 2 Mine of the Chi- cago, Wilmington, and Franklin Coal Company in WestFrankfort, Illinois, in 1951. These disasters led to passage oftheFederal Coal MineSafetyAct of 1952,in which federal mine inspectors were given limited en- forcement powertoprevent majordisasters.Hearings led to the closure of 518 unsafe mines. The 1960’s to the 2000’s The Federal Metal and Nonmetallic Mine Safety Act of 1966, which appliedtooperations at mines otherthan those producing coal and lignite, provided for the es- tablishment of mandatory standards addressing con- ditions or practices that could cause death or serious physical harm. Inspectors were empowered to stop op- erations thatwere deemed health-orlife-threatening. In 1968, a series of explosions at Consolidation Coal’s Number 9 Mine in West Virginia killed 78 min- ers. In response, Congress passed the Federal Coal Mine Health and Safety Act of 1969. It established procedures for developing mandatory standards for the coal-mining industry and called for expanded health and safety research to eliminate or reduce the risk of healthimpairment, injury,or death. Inspectors were given authority to withdraw miners from danger- ous areas. It also provided benefits for miners dis- abled by black lung disease. (A 1965 survey had found more than 100,000 active or retired coal miners in the United States suffering from black lung disease.) In 1973, the secretary of the interior separated the USBM’s regulatory function from its mining research function by establishingtheMining Enforcement and Safety Administration (MESA). MESA was responsi- ble for administering the 1966 and 1969 mine safety acts, which included enforcing mining health and safety regulations, assessing penalties for violating those regulations, prioritizing education and training in mining health and safety, and developing manda- tory health and safety standards. The Federal Coal Mine Safety and Health Amend- ments Act of 1977 provided the first single piece of comprehensive legislation for all types of mining oper- ations and extended theresearch directivesofprevious legislation to all segments of the mining industry. Un- der this act, MESA became the Mine Safety and Health Administration (MSHA) of the Department of Labor. With the closure of the U.S. Bureau of Mines in 1996, the Department of Energy assumed responsibility for conducting mine safety and health research. In 2002, at the Quecreek Mine in Pennsylvania, nine miners were trapped for a period of seventy-eight hours; all nine were rescued, indicating the progress that had been made in mine safety and accident prevention. Karen N. Kähler Further Reading Eisler, Ronald. Biogeochemical, Health, and Ecotox- icological Perspectives on Gold and Gold Mining. Boca Raton, Fla.: CRC Press, 2004. Given, Ivan A., ed. “Health and Safety.” In SME Mining Engineering Handbook. 2 vols. New York: Society of Mining Engineers, American Institute of Mining, Metallurgical, and Petroleum Engineers, 1973. Karmis, Michael, ed. Mine Health and Safety Manage- ment. Littleton, Colo.: Society for Mining, Metal- lurgy, and Exploration, 2001. Kirk, William S. The History of the Bureau of Mines. Com- memorative ed. Washington, D.C.: U.S. Depart- ment of the Interior, Bureau of Mines, 1996. Lindbergh, Kristina, and Barry Provorse. Coal: A Con - temporary Energy Story. Rev. ed. Edited by Robert Conte. Seattle: Scribe, 1980. 766 • Mining safety and health issues Global Resources McAteer, J. Davitt. Monongah: The Tragic Story of the Worst Industrial Accident in U.S. History. Morgan- town: West Virginia University Press, 2007. Newhouse, Terrance V., ed. Coal Mine Safety. Haup- pauge, N.Y.: Nova Science, 2009. Sloane, Howard N., and Lucille L. Sloane. A Pictorial History of American Mining: The Adventure and Drama of Finding and Extracting Nature’s Wealth from the Earth, from Pre-Columbian Times to the Present. New York: Crown, 1970. U.S. Congress, House Committee on Education and Labor. Evaluating the Effectiveness of MSHA’s Mine Safety and Health Programs: Hearing Before the Com- mittee on Education and Labor, U.S. House of Represen- tatives, One Hundred Tenth Congress, First Session, Hearing Held in Washington, D.C., May 16, 2007. Washington, D.C.: U.S. Government Printing Of- fice, 2007. Web Sites National Institute for Occupational Safety and Health National Academy Review Briefing Documents: The Mining Program http://www.cdc.gov/niosh/nas/mining U.S. Department of Labor, Mine Safety and Health Administration Safety and Health Topics http://www.msha.gov/S&Htopics.htm See also: Asbestos; Bureau of Mines, U.S.; Coal; De- partment of the Interior, U.S.; Health, resource ex- ploitation and; Methane; Strip mining; Underground mining. Mining wastes and mine reclamation Category: Pollution and waste disposal Mining and related operations generate waste materi- als that mar the landscape and pose a threat to human health and the environment. Reclamation and pollu- tion-control efforts minimize the impact of mining on its surroundings and makethe land fitfornonmining use. Background Humankind is dependent on mineral resources ex - tracted from theEarth. Theseresources cannot beob - tained without impacting the environment. Mining involves not only the mine itself—either a large, open excavation or a small surface opening leading to ex- tensive subsurface workings—but also access roads, utilities such as water and power, processing facilities, and other support buildings and equipment. These all take a toll on their surroundings, as do the solid, liquid, and gaseous wastes produced during mining, milling, and smelting. Unconstrained mining opera- tions andwastescan alter andlitterthe landscape, pol- lute surface water and groundwater, foul the air, harm plant and animal life, threaten human health and safety, and render land useless for subsequent pur- poses. As the world’s human population grows and the overall standard of living continues to rise in both de- veloped and undeveloped countries, the demand for mineral resources increases. Likewise, there are in- creasing and often conflicting demands upon the land where those resources are found. Wise manage- ment of mining wastes and reclamation efforts after mining makes it possible to use land for timber, crops, grazing, recreation, or other nonmining purposes once mineral wealth has been extracted from it. Mining Wastes and Their Impact During mining operations, rock that does not contain economically significant concentrations of anore must be removed. This waste material is known as spoil. In the case of surface mining, extensive areas are dis- rupted and laid bare as the vegetation, topsoil, and rock overlying the desired ore are stripped away. Dur- ing ore processing, additional solid waste is generated in the form of tailings, the portions of washed or milled ores that are too poor to merit further process- ing. Surface-mined areas and piles of spoil and tail- ings generally cannot support vegetation without first undergoing treatment; as a result, they are vulnerable to erosion and flooding. Silt from these unvegetated slopes finds its way into streams and other surface wa- ters, where it impacts aquatic life. The barren waste materials remain unstable, increasing the likelihood of landslide. Substantial piles of spoil or tailings can also be a physical obstruction to continued mineral exploration in the area. At mines where pyrite (iron sulfide) is associated with the ore body and water is present, acid mine drainage can result. Exposed pyrite breaks down in the presence of oxygen to form iron sulfate and sulfur dioxide. The decay of pyrite is self-perpetuating; as Global Resources Mining wastes and mine reclamation • 767 . the Mine Safety and Health Administration (MSHA) of the Department of Labor. With the closure of the U.S. Bureau of Mines in 1996, the Department of Energy assumed responsibility for conducting. York) This series of disasters led Congress to pass the Or - ganic Act of 1910, which established the U.S. Bureau of Mines (USBM) under the Department of the Inte- rior. The idea of such a bureau,. a loose, open structure consisting of sheets of atoms. Oxides and Hydroxides Chemically, the oxide and hydroxide minerals consist of metal ions (of either one or two types of metals) combined with oxygen