Encyclopedia of Global Resources part 30 doc

dated to 5200 b.c.e. By 3400 b.c.e., the fossil record shows a marked change in corn, notably increased cob and kernel size, indicating greater domestication. Fully domesticated corn (which could not survive without human help) had replaced the wild andother early types of corn by 700 c.e. Extensive attempts at hybridization began in the late nineteenth century, but the increase in yield was usually a disappointing 10 percent or so. By 1920, researchers had turned to inbreeding hybridization programs. In these, corn is self-fertilized, rather than being allowed to cross-pollinate naturally. Following a complex sequence of crossing and testing different varieties, the lines with the most desirable traits were put into commercial use, and they often produced 25 to 30 percent gains in yield. Although these early hy- brids focused on increasing the yield, researchers later began to look for insect-resistant and disease- resistant qualitiesaswell.Oneofthehybridizers of the 1920’swasHenry A. Wallace, founder of Pioneer Seed Company (the world’s largest seed company) and later U.S. vice president under Franklin D. Roosevelt. By the 1950’s, hybrid corn varieties were in wide- spread use. Obtaining Corn Corn processing takes place in one of three ways: wet milling, dry milling, or fermentation. In wet milling, corn is soaked in a weak sulfurous acid solution, ground to break apart the kernel, and then separated. The resulting by-products are found nearly every- where. Dry milling is a simpler process, involving the separation of the hull from the endosperm (the food storage organ, which is primarily starch in most corn) and the germ (the plant embryo) by repeated grind- ing and sieving. Fermentation of corn changes the starch to sugar, which is then converted by yeast to al- cohol. The process eventually results in ethyl alcohol, or ethanol (which is blended with gasoline to reduce carbon monoxide emissions), acetone, andothersub- stances. Uses of Corn The types of corn still in use are dent, flint, flour, pop, and sweet. Dent corn, characterized by a “dent” in the top of each kernel, is the most important commercial variety. Flint corn tends to be resistant to the rots and blights known to attack other types; it is also more tol - erant of low temperatures and therefore appears at the geographical edge of corn’s range. Flour corn is known for its softkernel, making it easier to grindinto flour and thus popular for hand-grinding. A mainstay at American movie theaters and as a snack food, pop- corn will, with an optimum moisture content of about 13 percent, explode to as much as thirty times its origi- nal volume when heated. Also popular in the United States and eaten fresh, sweet corn is so named be- cause, unlike other types, most of the sugars in the kernel are not converted to starch. Commercially, corn is used mostly for livestock feed and industrial processing. It is high in energy and low in crude fiber but requires supplements to make a truly good feed. Industrial processing creates a great variety of products found in everyday life— underscoring the importance of corn to the world’s economy. The cornstarch from wet milling supplies corn syrup (it is sweeter than sugar and less expensive, and billions of dollars’ worth is produced for soft drink manufacturers each year), starches used in the textile industry, ingredients for certain candies, and sub- stances used in adhesives, to name a few. Other by- products provide cooking oil; oil used in mayonnaise, margarine, and salad dressing; soap powders; and livestock feed. Dry milling produces hominy, grits, meal, and flour, all of which are used for human con- sumption. Brian J. Nichelson Further Reading Fussell, Betty. The StoryofCorn. NewYork: Knopf,1992. Mangelsdorf, Paul C. Corn: Its Origin, Evolution, and Improvement. Cambridge, Mass.: Belknap Press of Harvard University Press, 1974. Pollan, Michael. “Industrial Corn.” In The Omnivore’s Dilemma: A Natural History of Four Meals. New York: Penguin Press, 2006. Smith, C. Wayne, Javier Betrán, and E. C. A. Runge. Corn: Origin, History, Technology, and Production. Hoboken, N.J.: John Wiley, 2004. Sprague, G. F., and J. W.Dudley, eds. Corn and Corn Im- provement. 3d ed. Madison, Wis.: American Society of Agronomy, 1988. Wallace, Henry A., and William L. Brown. Corn and Its Early Fathers. Rev. ed. Ames: Iowa State University Press, 1988. Warman, Arturo. Corn and Capitalism: How a Botanical Bastard Grew to Global Dominance. Translated by Nancy L. Westrate. Chapel Hill: University of North Carolina Press, 2003. 260 • Corn Global Resources White, Pamela J., and LawrenceA.Johnson,eds.Corn: Chemistry and Technology. St. Paul, Minn.: American Association of Cereal Chemists, 2003. Web Sites U.S. Department of Agriculture, Economic Research Service Corn http://www.ers.usda.gov/Briefing/Corn U.S. Department of Agriculture, Economic Research Service Feed Grains Database http://www.ers.usda.gov/Data/FeedGrains See also: Agricultural products; Agriculture indus- try; Biofuels; Ethanol; Horticulture; Plant domestica- tion and breeding. Corundum and emery Category: Mineral and other nonliving resources Where Found Corundum occurs in a number of geological environ- ments. The most important of these are contact meta- morphic zones, silica-poor igneous rocks, pegmatites, and placers. The principal producer of corundum is South Africa, but commercial deposits also exist in Canada, India, Madagascar, and Russia. Minor depos- its are found in North Carolina and Georgia. The fin- est rubies and sapphires have always been mined in Asia: rubies from Burma, India, and Thailand; sap- phires from Sri Lanka, India, and Thailand. Turkey is the world’s leading producer of emery, with other significant deposits found on the Greek is- land of Naxos and in the Ural Mountains of Russia. In the United States, the most important emery deposits are around Peekskill, New York. The United States ex- ports no emery and imports most of what it consumes from Turkey and Greece. Primary Uses Corundum and emery are used as abrasives. In addi- tion, the transparent, colored varieties of corundum, ruby and sapphire, have long been prized as gems be - cause of their rarity and beauty. Technical Definition Corundum, another name for aluminum oxide (Al 2 O 3 ), is the second-hardestnaturalsubstance.Itoc- curs as an opaque material and as transparent gems. Emery is a natural mixture of corundum and magne- tite. Description, Distribution, and Forms Corundum, or aluminum oxide, can be categorized in two ways: as an abrasive and as a gem mineral. Both uses result from corundum’s extreme hardness (nine on the Mohs scale). Corundum as an abrasive has been largely replaced by alumina. Emery, named for Cape Emeri in Greece, is a natu- ral gray to black mixture of corundum and magnetite, usually with lesser amounts of spinel and hematite. The hardness of emery ranges from seven to nine, and its usefulness as an abrasive increases with the co- rundum content. Like corundum, emery has largely been replaced,butinthiscase by synthetic materials. History The gem varieties of corundum, ruby and sapphire, have a long history of use. Ruby attains its red color from the presence of chromic oxide. Sapphires occur in a varietyofcolors,butthosemostprizedasgems are colored deep blue by the presence of iron and tita- nium oxides. Beginning in the early twentieth cen- tury, both rubies and sapphires were synthesized. Even the prized “star” varieties can be manufactured, and the synthetic gems are virtually indistinguishable from their natural counterparts. Obtaining Corundum and Emery Both corundum and emery are obtained through mining, the later of which has been mined in Greece for more than two thousand years. However, most co- rundum and emery are now obtained synthetically. Uses of Corundum and Emery Corundum has limited use as crushed grit or powder for polishing and finishing optical lenses and metals and isusedonpaper,cloth,andabrasivewheels. As co- rundum wears, small pieces constantly flake off to form fresh edges, enhancing its ability to cut. In addi- tion to their value as gems,syntheticrubies are used in industrial and medical lasers. Emery finds some applications on coated abrasive sheets (emery cloth), as grains and flour for polishing glass and metal surfaces, on grinding wheels, and on Global Resources Corundum and emery • 261 nonskid pavements and stair treads. Emery forms principally by contact metamorphism in limestones. Donald J. Thompson Web Site Corundum http://www.minerals.net/mineral/oxides/ corundum/corundum.htm See also: Abrasives; Gems; Metamorphic processes, rocks, and mineral deposits; Mohs hardness scale; Placer deposits. Cotton Category: Plant and animal resources Where Found Cotton (genus Gossypium) is grown within the tropical and subtropical regions of the world in areas that have adequate amounts of sunshine and fertile soil. In gen- eral, areas that receive 600 to 1,200 millimeters of rainfall annually are best suitedfor cotton production because the plant requires a large amount of water in order to grow well. However, dryland cotton farming occurs in areas with lower rainfall totals with the help of irrigation. Within the United States,mostofthe cotton crop is grown in Alabama, Arizona, Arkansas, California, Georgia, Florida, Kansas, Louisiana, Mississippi, Mis- souri, New Mexico, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia. Cot- ton is also commerciallyproducedinChina,India,Pa- kistan, Uzbekistan, Brazil, Australia, Egypt, Argen- tina, and Turkey. Primary Uses Cotton fibers are primarily used in the textile industry for the manufacture of clothing. Smaller amounts of cotton are used to produce fishing nets, cotton paper, tents, and gunpowder. In some parts of the world, cot- ton is still used to make mattresses. Refined cotton- seed oil is used as a vegetable oil in many foods, such as baked goods. Cottonseed hulls are often mixed in with other plant materials to form a roughage ration for cattle. Technical Definition Cotton is a plant in the mallow family, Malvaceae. This botanical group is a large family containing a number of plants important to horticulture, including the hi- biscus. Cotton plants may grow to aheightof3meters, but most commercial varieties have been bred to be shorter for easier harvesting. The plant has leaves with three to seven lobes; the ovary of the cotton flower is a capsule or boll, which, when ripe, opens along the dark brown carpels to reveal the usually white inner fibers. Longer fibers are known as staples, while shorter fibers are called linters. When separated from one another by a process known as ginning, the fibers can be woven into cotton yarn and used for tex- tile manufacturing. Description, Distribution, and Forms Four species of cotton—Gossypium hirsutum, G. bar- badense, G. arboreum, and G. herbaceum—are commer- cially produced, with G. hirsutum accounting for about 90 percent of the world’s production. Approxi- mately 8 percent of the world’s cotton is produced from G. barbadense, and the remaining 2 percent comes from G. arboreum and G. herbaceum. G. hirsutum,up- land cotton, is native to Florida, the Caribbean, Mex- ico, and Central America and is the cotton with which most Americans are familiar. G. barbadense is a plant of tropical South America and is known commercially as pima cotton. Tree cotton, G. arboreum, is native to In- dia and Pakistan, while the last commercially impor- tant species, G. herbaceum, is foundin the Arabian Pen- insula and southern Africa and is known as levant cotton. In addition to the four commonly cultivated spe- cies of cotton, five noncommercial species of this ge- nus are found in tropical and subtropical areas of the world. These include G. australe and G. sturtianum, both found in Australia; G. darwinii, which grows in the Galápagos Islands; G. thurberi, a plant of northern Mexico and Arizona;andG.tomentosum,aHawaiianIs- land endemic. Cotton is one of the most pesticide-intensive of all cultivated crops. Genetically modified cotton was de- veloped in the twentieth century in an attempt to alle- viate some of the cotton farmer’s dependence upon pesticide use. The bacterium Bacillus thuringiensis pro- duces a natural pesticide that is toxic to a number of insects, most notably members of the insect orders Coleoptera (beetles) and Lepidoptera (butterflies and moths). By inserting within cotton tissues the 262 • Cotton Global Resources B. thuringiensis gene that codes for this specific toxic - ity, geneticists were able to develop cotton varieties that were resistant to some of the important pests, such as boll weevils and bollworms. In recent years, some of this cotton has been found to be no longer re- sistant to pests. A small percentage of commercially grown cotton is produced with organic methods. No insecticides are used on organically grown cotton, and crop rota- tion is a technique used in an attempt to keep the soil fertile and to discourage pests. History Cotton has been cultivated by a number of cultures for at least six thousand years. The ancient peoples of India, China, Egypt, and Mexico all grew and made use of cotton in weaving textiles. The fiber has been extensively traded throughout both the Old and New Worlds for the past two thousand years. During the first century c.e., traders from the Middle East brought fabrics such as calico and muslin to markets in southern Europe. GreatBritain’s famous East India Company brought cotton cloth from India during the seventeenth century. Raw cotton was imported from the American colonies in the 1700’s, and this import spurred a need for the development of machinery that could process and spin the cotton.Advances such as the spinning jenny, developed in 1764, and Sir Richard Arkwright’s spinning frame, developed in 1769, enabled Britain to produce cotton yarn and cloth with increased speed and efficiency. American Eli Whitney’swell-known1793inventionofthecotton gin allowed cotton seeds tobe easily stripped from the fibers. During the American Civil War, Britain could not obtain cotton from the United States and so bar- gained with Egypt for its supply. After the war, how- ever, Britain turned again to buying its cotton from the United States, and the resulting loss of trade was a severe blow to the Egyptian economy. Cotton contin- ued to be a staple crop for the southern United States throughout the 1800’s and 1900’s and remains a pri- mary export crop for the country. Obtaining Cotton In traditional cotton farming, cotton fields are cleared of old plants from the previous growing sea- son and thoroughly plowed into rows. The farmer may clear fields in the winter or wait until early spring before planting. Cotton seeds are planted mechani - cally in the spring, when the soil is warm enough for seeds to germinate. Germination occurs in five to ten days if adequate soil moisture is available; a full stand of cotton is generally present in eleven days if germi- nation is successful. Within five to seven weeks “squares” (cotton flower buds) open to produce a creamy yellow flower that self-pollinates within three days. As the flower maturesit changes color from light yellow to pink to darker red before falling off the plant to reveal the tiny “boll.” Approximately forty- five to eighty days after the bolls form, they split along the carpels of the fruit to reveal white fibers. A boll may contain as many as 500,000 of these fibers, which are called staples. Staple length varies among the dif- ferent cotton species, with upland cotton having sta- ple lengths of 0.81 inch to 1.25 inches and pima cot - ton having lengths of 1.31 inches to 1.5 inches. If the cotton is to be mechanically picked, it must Global Resources Cotton • 263 A woman inIndiabrings a bundle oforganic cotton to thetown cen- ter to be ginned. (AP/Wide World Photos) first be defoliated, so that leaves will not be picked along with the cotton bolls. After completing the de- foliation, cotton pickers can drive through the fields and pick the cotton as long as it is dry. Moisture, from either dew or rain, damages the cottonfibers once the bolls have opened, so farmers hope for dry weather during harvesting. Picked cotton is formed into bales weighing 218 ki- lograms each; thirteen to fifteen bales may then be formed into modules and transported to the cotton gin. The ginning process fluffs the cotton and cleans it of dirt, plant trash, and seeds. Cleaned cotton is compressed again into bales, which are inspected; if cleared for sale, the bales are stored in a temperature- and moisture-controlled warehouse until being moved to a processing facility. Worldwide, 31.3 million hectares of cotton were planted in 2008, with 112.9 million 218-kilogram bales produced. China leads the world in cotton produc- tion, with 25.3 million bales produced in 2007. India, the United States, Pakistan, and Brazil complete the list of the top five cotton-producing countries. Uses of Cotton Cotton’s primary use is in the manufacture of textiles. Although there are many different types of cotton fab- ric, some of the best known include terrycloth, a soft fabric used to make bath cloths, towels, and robes; denim, used in jean manufacture, which can be dyed a variety of colors but usually is dyed blue; chambray, a soft, blue cloth from which work shirts are made; and corduroy and twill, from which heavier, sturdier items of clothing are made. Cotton yarn is used in quilt making. Egyptian cotton is often used to pro- duce bedsheets and pillowcases. After cotton seeds are removed from raw cotton during the ginning process, cottonseed oil can be re- fined and used as a vegetable oil in cooking. It is also used in shortening and salad dressing and is a com- mon component of baked goods such as crackers and cookies. Cottonseed meal and cottonseed hulls are fed to ruminant livestock such as cattle and goats, and the meal can be fed to fish and poultry. Nonruminant mammals are unable to eat cottonseed products be- cause of a toxic chemical, gossypol, which will sicken and possibly kill these animals. Strong fishnets and tents can be made from cotton fibers. When exposed to nitric acid, cotton can be used to form “guncotton” or “smokeless powder,” a type ofexplosivethatissaferto use than black powder. Cotton fibers have been used for many years in the production of paper and as binding for books. Cotton paper is stronger than wood-pulp-based paper and re- tains ink better. Therefore, it is often used to produce paper money and archival copies of important books and documents. Lenela Glass-Godwin Further Reading Hake, S. Johnson, T. A. Kerby, and K. D. Hake. Cotton Production Manual. Oakland: University of Califor- nia, Division of Agriculture and Natural Resources, 1996. Smith, C. Wayne. Crop Production: Evolution, History, and Technology. New York: John Wiley and Sons, 1995. Smith, C. Wayne, and Joe Tom Cothren. Cotton: Ori- gin, History, Technology, and Production. New York: John Wiley and Sons, 1999. Tripp, Robert Burnet. Biotechnology and Agricultural Development: Transgenic Cotton, Rural Institutions, and Resource-Poor Farmers. New York: Routledge, 2009. Web Sites National Cotton Council of America http://www.cotton.org/ Sustainable Cotton Project http://www.sustainablecotton.org/ See also: Agricultural products; Agriculture indus- try; Agronomy; American Forest and Paper Associa- tion; Botany; Farmland; Flax; Hemp; Irrigation; Paper; Paper, alternative sources of; Plant fibers; Renewable and nonrenewable resources; Textiles and fabrics. Council of Energy Resource Tribes Category: Organizations, agencies, and programs Date: Established 1975 The Council of Energy Resource Tribes (CERT) seeks fair payment for resources pumped or mined on Ameri- can Indian reservation land and advises tribes re - garding conservation, lease arrangements, royalties, and economic development. 264 • Council of Energy Resource Tribes Global Resources Background The Council of Energy Resource Tribes was founded by a group of tribal leaders seeking to monitor and re- ceive appropriate payment for energy resources on American Indian land. Historically, tribes had been underpaid, sometimes scandalously, for mineral re- sources obtained on their lands. The leasing policies of the U.S. Bureau of Indian Affairs (BIA) engen- dered considerable controversy and resentment; the BIA frequently allowed corporations to obtain oil, coal, and other resources from American Indian land for prices well under market value. Moreover, leasing royalties sometimes were underpaid or went unpaid altogether. Estimates indicate that energy resources contained on American Indian land account for 10 percent of the U.S. total. One of the founders of CERT, Peter MacDonald, a Navajo who was CERT’s first elected chair, referred to these resources as wealth “so vast it has not yet been measured.” CERT set out to inven- tory the resources of the tribes of the West and found that they controlled one-third of U.S. coal and ura- nium resources and large supplies of petroleum and natural gas. CERT began to demand higher royalties for coal, oil, and uranium mined on American Indian lands and worked to integrate variousaspects of reser- vation energy development. Impact on Resource Use The founders of CERT had noted the activities of the Organization of Petroleum Exporting Countries (OPEC) as an influential international energy re- source organization, and they hoped to achieve simi- lar influence over tribal resources as they entered the domestic market. CERT helps tribes negotiate contracts regarding resources found on reservation lands. It provides on-site technical assistance and ad- vice in the areas of conservation, resource manage- ment, and economic development. CERTwasfounded by leaders from twenty-five tribes; by the end of the first decade of the twenty-first century, it had more than sixty tribal members. The organization’s head- quarters are in Denver, Colorado. Vincent M. D. Lopez Web Site Council of Energy Resource Tribes http://www.certredearth.com/ See also: Coal; Oil and natural gas distribution; Oil embargo and energy crises of 1973 and 1979; Oil in- dustry; Organization of Petroleum Exporting Coun- tries; Uranium. Cropland. See Farmland Crystals Category: Mineral and other nonliving resources Crystals are composed of regularly repeating three- dimensional patterns of atoms or ions; a crystal is therefore a highly ordered structure. Crystals have a number of electronic and scientific applications, in- cluding uses in optics and in radio transmitters (piezo- electric quartz crystals). Well-formed crystals are also prized by collectors, and crystals of gem minerals are cut into jewelry. Background Crystals are solids that naturally display smooth pla- nar exterior surfaces called “faces,” which form dur- ing the growth of the solid. These faces collectively produce a regular geometric form that mimics the or- derly internal atomic arrangement of the elements present in the solid. Some scientists use the term “crystal” to refer to any solid having an ordered inter- nal atomic structure regardless of whether the solid displays faces. However, most scientists use the word “crystalline”forsuchsolidswhen no faces are present. Many solids display a cleavage, a flat planar surface formed when the solid is broken; cleavage fragments are sometimes mistaken for crystals. Crystals are described and classified according to the symmetrical relationship existing between the faces. The fundamental way of describing a crystal is to list the “forms” that it displays. Scientists recog- nize a total of forty-eight different forms, many desig- nated by common geometric terms such as cube, octahedron, tetrahedron, pyramid, and prism. Most crystals display multiple forms. For example, quartz crystals display one prism and at least two sets of pyra - mids. Considering every possible symmetrical arrange - ment of faces, every crystal can be placed into one Global Resources Crystals • 265 of thirty-two groupings called crystal classes. These classes are further grouped into six crystal systems based on similar symmetry characteristics. The names of the six systems, from most to least symmetrical, are isometric, hexagonal, tetragonal, orthorhombic, monoclinic, and triclinic. Where Crystals Are Formed Large crystals can develop when the faces growing in a melt, solution, or gas are unimpeded by other surrounding solids. This situation commonly occurs where open cracks and cavities exist in rock and the liquid or vapor from which the crystal is growing has free access to the open space. The largest crystals are found in igneous pegmatites. The Etta pegmatite in the Black Hills of South Dakota contained a 12-meter crystal weighing more than 18 metric tons. The larg- est known crystal was a single feldspar from a pegma- tite in Karelia, Russia, that weighed several thousand metric tons. Crystalsarealsofoundalong fault planes, in hot springs areas, around vents for volcanic gases, and in cavities within igneous and sedimentary rocks where underground water is circulating. Another mechanism for the growth of crystals occurs during the process of metamorphism. Preexisting rocks that are subjected to elevated temperatures and pressures within the Earth can recrystallize while still solid. During this metamorphism some of the new minerals that form have a strong surface energy and will de- velop faces even while in contact with other growing minerals. The growth conditions discussed above are so com- mon within the Earth that crystals can be found in al- most every state in the United States and every coun- try in the world. It is impossible to specify all the important occurrences of large, well-formed crystals. Some of the more notable classic localities in the United States include quartz in Hot Springs, Arkan- sas, and Herkimer County, New York; galena in the tristate district of Missouri, Kansas, and Oklahoma; zinc-bearing minerals in Franklin, New Jersey; garnets at Gore Mountain, New York; iron oxides in the upper peninsula of Michigan; and fluorite and celestite at Clay Center, Ohio. Uses of Crystals Particularly well-formed crystals are highly prized by collectors and museums. Most crystals, however, are 266 • Crystals Global Resources Amethyst crystals are purple in color and are often used as gemstones. (©iStockphoto.com) more valuable for their chemistry or as crystalline sol - ids. Many crystals are crushed during the processing of ore minerals. It was a common practice for miners to save the larger, better-formed crystals from the crushing mill because they were worth more as speci- mens for collectors than they were worth as ore mate- rial. Most crystals of gem minerals are cut and faceted to make jewelry. A large diamond crystal, for exam- ple, is worth more as a well-faceted gemstone than as a crystal specimen. There are a growing number of technological uses of “crystalline solids” where the systematic internal arrangement of atoms can produce a variety of de- sirable physical phenomena useful in the fields of electronics and optics. As an example, very pure untwinned quartz is called “opticalgradecrystal” even though it lacks faces. Quartz crystal is cut, ground, and made into lenses and prisms for optical instruments and is also used in radio oscillators, timing devices, and pressure gauges in the electronics industry. Crystal Defects and Growth Rates Crystal defects occur naturally as crystals are formed; they are also sometimes introduced artificially, as they have useful electrical, mechanical, and optical quali- ties. A growing crystal typically requires the proper placement of trillions of atoms per hour. About one atom in every one hundred thousand is misplaced to form a defect. These defects can be point disorders, or they can geometrically be combined to form line, plane, or three-dimensional disorders. The Schottky defect is a point disorder in which an atom is missing from the spot it should occupy, leaving a hole in the pattern. The Schottky defect results when a second layer of atoms is quickly deposited before all the posi- tions can be filled in the first layer. The Frenkel defect occurs when an atom is out of its proper position and can be found nearby, inappropriately stuck between other atoms. The impurity defect is yet another point disorder, occurring when an atom of a foreign ele- ment (an impurity) either substitutes for the normal atom or is stuffed between the proper atoms of the structure. Coloration can be caused by various point defects. When an electron is captured by the hole of a Frenkel defect it will absorb energy from passing light and be- come what is known as a “color center.” An abun- dance of Frenkel color centers in fluorite will give the crystal a purple color. An impurity defect can be ac - companied by a shift in electrons, also causing a color center. Smoky quartz is caused by color centers result - ing from impurity defects. The electron shifts are ei- ther induced by low levels of radiation in the Earth over geological time or by artificial exposure to an in- tense X-ray or gamma-ray beam for a few minutes. A significant number of thesmokyquartz crystalson the market began as natural colorless quartz that has been irradiated. Line disorders are linear defects and are com- monly called “dislocations”becausetheycreate an off- set within the crystal. The most common is an edge dislocation resulting when an entire plane of atoms is pinched out and terminated as adjacent planes on ei- ther side begin to bond directly together. When crys- tals are stressed they will often deform by slipping along linear disorders. Crystals can also become deformed or malformed because of variations in the growth rates of different faces or different parts of the crystal. When the chem- istry of the growing solution begins to lack the atoms needed by the crystal, then the faces can stop growing while the edges where faces meet will continue to grow. In extreme instances the resulting malformed crystal has a skeletal look, showing a network of edges with- out any faces, yet all the symmetricalforms are still evi- dent, allowing proper classification of the crystal. Twinning During formation, a solid may produce a symmetrical intergrowth of two or more crystals. When the inter- growth is crystallographically controlled, the result- ing composite is called a twinned crystal. The individ- ual crystals within the twinned aggregate are related to one another by a different symmetrical element— one that is not seen in any of the individual parts. This often results in a symmetrical, exotically shaped ag- gregate that does not appear to belong to any single crystal class. Crystals displaying exceptional twins can be more valuable for their twinning than as mineral specimens. History of Crystals Crystals have a history that reaches back into the realm of legends and myths. An important early work that combined legend with the first sound science was the thirty-seven-volume Historia Naturalis, written by Pliny the Elder in the first century. Pliny described many real as well as nonexistent crystals, which he stated were formed by such exotic processes as “the light of the moon” or “the purge from the sea.” Global Resources Crystals • 267 Nicolaus Steno established the first law of crystallog - raphy in 1669, known as the law of constancy of inter- facial angles. The law holds that for all crystals of a given mineral the angles measured between similar faces are always exactly the same. This law allows for the positive identification of deformed or malformed crystals simply by measuring the angles between exist- ing faces. In 1781, René-Just Haüy was the first to rec- ognize that a crystal is composed of a large number of smaller particles arranged in a regular geometric or- der such that it fills space without gaps. This was a re- markable advance, considering that it preceded the concept of the atom in chemistrybymorethan twenty years. In 1830, based on graphical and mathematical considerations, Johann Hessel predicted the exis- tence of thirty-two classes of symmetry corresponding to modern crystalclasses.Inthe1920’s, two crystallog- raphers, C. H. Hermann and Charles-Victor Mau- guin, developed the notation that is used to designate the symmetrical arrangement of faces found on any crystal. Dion C. Stewart Further Reading De Graef, Marc, and Michael E. McHenry. Structure of Materials: An Introduction to Crystallography, Diffrac- tion, and Symmetry. Cambridge, England: Cam- bridge University Press, 2007. Klein, Cornelis, and Barbara Dutrow. The Twenty-third Edition of the Manual of Mineral Science. 23d ed. Hoboken, N.J.: J. Wiley, 2008. Read, P. G. Gemmology. 3d ed. Boston: Elsevier/ Butterworth-Heinemann, 2005. Smyth, Joseph R., and David L. Bish. Crystal Structures and Cation Sites of the Rock-Forming Minerals. Boston: Allen & Unwin, 1987. Tilley, Richard J. D. Crystals and Crystal Structures. Hoboken, N.J.: John Wiley, 2006. Wenk, Hans-Rudolf, and Andrei Bulakh. Minerals: Their Constitution and Origin. New York: Cambridge University Press, 2004. See also: Gems; Geodes; Hydrothermal solutions and mineralization; Minerals, structure and physical properties of; Pegmatites; Quartz. 268 • Crystals Global Resources D Daly, Marcus Category: People Born: December 5, 1841; Derrylea, County Cavan, Ireland Died: November 12, 1900; New York, New York Marcus Daly, an Irishman with few job skills and little education, immigrated to the United States and be- came, in one-quarter of a century, one of three “copper kings” in the United States. After he discovered that his silver mine at Anaconda in Montana contained a large copper vein beneath the silver, he successfully ex- ploited the copper and virtually made “Anaconda” a household word in the United States. Biographical Background The youngest of eleven children in an Irish family in County Caven, Ireland, Marcus Daly was born Decem- ber 5, 1841. Five yearsafter immigrating to the United States at the age of fifteen, Daly sailed to San Fran- cisco, then worked at a silver mine of the Comstock Lode in Virginia City, Nevada. By 1871, he was a fore- man in Ophir, Utah, for the Walker Brothers mining syndicate. There he met and married MargaretEvans; they had three daughters and a son. When Daly was sent to the Montana Territory to acquire a silver mine for Walker Brothers, he kept a one-fifth interest for himself. He sold that interest in 1876 and, with addi- tional backing, purchased the Anaconda claim. In addition to his mining career, Daly was a horse owner and breeder and the founder of the influential Anaconda Standard newspaper. He died at the Nether- lands Hotel in New York City at age fifty-eight. His re- mains are in a mausoleum in Greenwood Cemeteryin Brooklyn, New York. Impact on Resource Use The Anaconda mine was principally a silver mine un- til Daly discovered a copper vein about 91 meters deep and 30 meters wide beneath the silver vein. By this time, copper was coming into use for electricity and telegraph wire. While the price of copper in the early 1880’s was only around $0.35 to $0.45 per kilo - gram, smelting costs were high because the ore had to be shipped to Swansea, Wales, to be smelted. Daly was determined to reduce those costs and realize a profit. With financial backing, he built the town of Ana- conda, Montana, where he built his own smelter and connected it by rail to nearby Butte. By 1890, the Butte copper mines saw an annual production of cop- per valued at more than $17 million. Daly bought coal mines and forests to supply the fuel and timber he needed and built his own power plants. From 1895 to 1980, the Anaconda smelter was a major employer. It closed because of a labor strike; one-quarter of Anaconda’s workforce became unem- ployed, an economic blow from which the town did not recover.Standard Oil bought the Anaconda Com- pany in 1899 and had a major impact on the economy of that area until the 1970’s. From the 1950’s to the 1970’s the Anaconda Copper Mining Company en- gaged in open-pit mining until copper prices col- lapsed, at which time the Atlantic Richfield Company (ARCO) bought the company. However, ARCO ceased its mining operations in Butte in 1982, bringing to a close what Daly had begun almost one century earlier and leaving a pit containing heavy metals and danger- ous chemicals. A plan to solve the groundwater prob- lem was instigated during the 1990’s. Victoria Price See also: Copper; Mining safety and health issues; Mining wastes and mine reclamation; National Park Service; Smelting. Dams Category: Obtaining and using resources Dams are designed for a number of purposes, includ- ing conservation and irrigation, flood control, hydro- electric power generation, navigation, and recreation; most major dams have been constructed to serve more than one of these purposes. Background A dam is an artificial facility that is constructed in the path of a flowing stream or river for the purpose of . CERT set out to inven- tory the resources of the tribes of the West and found that they controlled one-third of U.S. coal and ura- nium resources and large supplies of petroleum and natural gas “the light of the moon” or “the purge from the sea.” Global Resources Crystals • 267 Nicolaus Steno established the first law of crystallog - raphy in 1669, known as the law of constancy of inter- facial. royalties, and economic development. 264 • Council of Energy Resource Tribes Global Resources Background The Council of Energy Resource Tribes was founded by a group of tribal leaders seeking to monitor and