Encyclopedia of Global Resources part 34 pot

In the United States, cool deserts (sagebrush grass and salt-desert shrub types) occur in old lake beds. Ancient Lake Bonneville in northern Utah and Lake Lahontan in Nevada once occupied much larger ar- eas and dominated the landscape. These deserts are also influenced by the Sierra Nevada and Cascade Mountain ranges, which cast a rain shadow effect on their eastern valleys. Intermittent drainages (wadis or arroyos) often cut across desert landscapes; they con- tain running water only during or immediately after a rainfall event. These drainages support unique vege- tation and serve as important habitats for birds and other animals. Another major feature of deserts is that nutrients are often limiting. Soil nitrogen and organic matter are especially low in these ecosystems. Free-living and symbiotic nitrogen-fixing bacteria arescarce in deserts. Research indicates that lichens and algae, forming crusts on desert soils, may be the major source of soil nitrogen for plant growth. Desert Adaptations Rainfall events occur infrequently in deserts. Both plants and animals must have adaptations to take ad- vantage of these episodic periods of available water to survive in these harsh environments. Thus one sees flushes of desert flowers during spring and summer months, especially in years when rainfall is abundant. These same flowers may not be seen again for several years. Desert plants exhibit several adaptations that al- low them to exist successfully under these stressful conditions. Some plants, such as mesquite, have deep root systems that allow access to deepsources of water. They do not have to rely on rainfall during the grow- ing season. Some plants have dense, shallow root sys- tems that allow them to tap soil water in the soil sur- face from light showers. Some plants have both types of root systems. Cactus and other succulents have the ability to store water in their tissues for use during pe- riods of low rainfall. Some plants, such as the creosote bush, shed many leaves to reduce transpirational re- quirements. Others havefewstomataontheirleafsur- faces, thereby reducing transpirational stress. These stomata tend to close and restrict transpiration. Des- ert soils are often high in salt content from surface evaporation ofrainfallthatdoesnotpenetratefar into the soil,andplantsgrowing on saline soilshavespecial adaptations for coping with these conditions. Animals also have many adaptations to desert condi - tions. Some desert animals can live in dormant stages during unfavorable periods. Many exhibit no definite breeding season and can breed whenever conditions are favorable. Some, including birds, can conserve water by reducing loss through concentrated urine. Some desert animals obtain most of their water through the food they eat. Many are nocturnal, thereby avoid- ing the high temperatures of the day. Intermediate- sized and small mammals often burrow to escape the heat and find more favorable conditions. Conservation and Prevention Issues Desert plants andanimals are frequently under threat from a variety of natural and human-related activities. Since water resources are so scarce, any external fac- tor that changes the water cycle or the availability of water at critical times may threaten organisms. In some cases the existence of desert plants and animals is not obvious, and adequate information on their sta- tus is lacking. Many desert landscapes were formed by erosion, but changes may be very slow and difficult to ascer- tain. For example, there has been much concern over the increase in desert areas in the world. The word “desertification” has been used to describe the degra- dation of arid and semiarid areas into desertlike envi- ronments. For sometimenearlyallobservers believed that the Sahara Desert was expanding, but this has be- come a subject of debate. Detailed remote sensing analyses have suggested that the Sahara Desert may expand and contract, perhaps in response to climatic cycles. In many areas in Africa, such as the Sahel, live- stock populations are increasing to support the ex- panding human population. During the dry season, woody plants supply needed high-quality forage for these animals. These same woody plant resources are also heavily exploited for fuel wood despite re- strictions placed on their harvest. Depletion of these valuable woody plant resources could have serious consequences forthesedelicateecosystems. Other ex- amples of resource problems in desert areas include overhunting of native ungulates for animal products such as tusks. Natural Resources Deserts of the world hold most of the reserves of oil, natural gas, and coal, and they therefore serve as a source of natural wealth for many countries in the Middle East. These resources remained sufficient to supply energy needs into the twenty-first century, but with escalating costs, alternative energy sources will 300 • Deserts Global Resources become more important. Deserts also provide other minerals, such as silver, lead, diamonds (in southern Africa), and copper, but many deserts such as the Sa- hara are not important for mineral resources. Desert plants are also used as food by many native people. In the southwestern United States, American Indians used cactus fruits as a staple food. In the Sahel in northern Africa, the following types of foods were available in substantial quantities: rhizomes and fleshy stems, the seeds of forbs, grass seeds, fruits, ed- ible gums, and mannas. Fibers from desert plants are also used for basket weaving in many countries, and plant pigments are used as natural dyes. Vegetational Dynamics In desert regions of the United States and elsewhere, shrubby plants are increasing at the expense of grass- land. Reasons for this change are not clear, but several factors are probably important. Some workers have suggested that climatic changes have favored a shift from grasses to shrubs. Increased carbon dioxide concentration of the atmosphere from burning fossil fuels is one hypothesis. Others insist that the intro- duction of domestic livestock beginning in 1850 dis- rupted the ecological balance in favor of shrubs. Lack of fire to restrict development of shrubs in grassland has also been advanced as a possible cause. Several studies in southwestern deserts in the United States have shown that native mammals and rabbits can ex- ert considerable influence on vegetation and can re- duce grass cover and abundance. It is possible that all these factors, and probably others not considered, have together been responsible for changes in desert vegetation. Increases in shrubs, such as mesquite in theUnited States, eventually alter nutrient distribution patterns. In relatively uniform grasslands, soil nutrients are dis- tributed fairly evenly. As shrubs such as mesquite in- crease at the expense of grasses, however, the shrubs are able to take up nutrients from a much larger vol- ume of soil. These nutrientsthentendtobecomecon- centrated around the individual mesquite trees and to form islands of nutrient concentration. Interdune areas often suffer soil loss through wind erosion, and the soil accumulates around individual mesquite plants. If the soil is deep enough, mesquite dunes eventually form. Interdune areas with little surface soil are deficient in nutrients, especially nitrogen, and lack water-holding capacity. These changes also affect animal life. Some animals, such as bannertailed kan - garoo rats and pronghorn antelope, utilize grassland habitat and are favored by grassland. Others, such as those that feed on mesquite (insects and arthropods), are favored by the mesquite dunelands. Mining for coal and other minerals often disturbs desert ecosystems. Mines are limited in size and in the area affected, but they can leave conspicuous scars on the landscape, especially with deep open-pit mines. The area disturbed by the mines can be restored, but restoration is difficult and expensive. Rex D. Pieper Further Reading Evenari, Michael, Imanuel Noy-Meir, and David W. Goodall, eds. Hot Deserts and Arid Shrublands. New York: Elsevier, 1985. Goudie, Andrew. Great Warm Deserts of the World: Land- scapes and Evolution. New York: Oxford University Press, 2002. Laity, Julie. Deserts and Desert Environments. Hoboken, N.J.: Wiley-Blackwell, 2008. Quinn, Joyce Ann. Desert Biomes. Westport, Conn.: Greenwood Press, 2009. Sowell, John. Desert Ecology: An Introduction to Life in the Arid Southwest. Salt Lake City: University of Utah Press, 2001. Ward, David. The Biology of Deserts. New York: Oxford University Press, 2009. West, Neil E., eds. Temperate Deserts and Semi-Deserts. New York: Elsevier Scientific, 1983. Web Site U.S. Geological Survey Deserts: Geology and Resources http://pubs.usgs.gov/gip/deserts See also: Conservation; Desertification; Ecology; Ecosystems; Farmland; Geochemical cycles; Irriga- tion; Rangeland; Soil. Developing countries Categories: Countries; social, economic, and political issues Developing countries’ resources have helped to feed and fuel the world’s developed countries. As the devel - oping countries themselves industrialize, and as their Global Resources Developing countries • 301 populations grow, the demands on these resources in - crease, and the issues of resource constraints and envi- ronmental degradation rise on the political agenda. Background Developing countries are a diverse group, with tre- mendous variety in size, income, and industrial devel- opment. China and Singapore reflect the size dispari- ties, with the former measuring about 9.6 million square kilometers and the latter approximately 1,000 square kilometers. Of the 210 countries the World Bank categorizes as high, middle, or low income, 70 percent are classified as developing countries. Of these, 30 percent are categorized aslow-income coun- tries (with per capita earnings equivalent to $975 or less). These include Bangladesh, Chad, and Ethiopia. The Bahamas, Cyprus, Kuwait, and Qatar are among the 31 percent in thehigh-incomecategory. Although many of these countries are still very dependent on primary goods, a small number, including South Ko- rea and Venezuela, have undergone significant indus- trialization. Resource use in developing countries is condi- tioned by a web of global, national, and local factors. The nature of their economies and their relative lack of economic power combine to determine their pat- tern of resource use. This pattern is closely associated with the asymmetric economic relations between de- veloping countries and industrialized countries. Con- sumption patterns in industrialized countries high- light the variety of goods and services associated with a consumer culture; conversely, in most developing countries the focus is on basic needs. Industrialized countries are far greater consumers of commercial energy resources such asoil, natural gas, and coal. De- veloping countries, however, consume more wood and wood products, primarily as fuel wood and char- coal, and clearmoreoftheir forests, primarily for agri- culture. Resource use patterns change over time: In the past, industrialized countries engaged in substan- tial deforestation, and as developing countries indus- trialize during the twenty-first century, their use of commercialenergysourceswill increase significantly. In their efforts to satisfy both the interests ofthe in- dustrialized countries’ capital and their own needs, some developing countries extend the boundaries of their economies by exhausting soils, removing old- growth forests, or overexploiting fisheries. A combi - nation of forces operate at the global, national, and local levels to shape policies regarding development, trade, and investment—often with disastrous conse - quences for the environment. Local Factors Inequalities within the societies of developing coun- tries result in skewed patterns of access to land and other assets, with elites benefiting disproportionately. For example, in South American countries, 17 per- cent of the landowners control 90 percent of the land. Short-term needs can force landless families to farm fragile mountain slopes and torch rain forests in or- der to plant foods. In Brazil, poor people clear the for- ests to farm. Because of the fragility of the soils, in a short time yields diminish, and farmers must move on to other areas of rain forest. Similar practices result in the depletion and degradation of freshwater re- sources, soils, forests, and habitats. The poor are both agents and victims of environ- mental degradation, whether it is a result of their own actions or a consequence of consumption by higher- income groups. The poor have few or no alternatives when the environmental resources on which they depend are degraded. Dwindling food supplies, un- safe drinking water, polluted air, and unsanitary conditions contribute significantly to reduced life ex- pectancy and high child mortality. Moreover, long- standing traditional social and economic patterns encourage poor Third World people to have many children. The result is a vicious cycle: A large popula- tion leads to more poverty and increasingly threatens the renewable resources on which local populations depend. Thus, development and environment are inextri- cably linked: Development that alleviates poverty is essential if renewable resources are to be preserved in developing nations, and material redistribution is necessary. For sustainable use of natural resources to be feasible, people needtohavesomemeasure ofcon- trol of, and access to, resources. Case studies indicate that small holders who own their land tend to take care of it, unlike squatters and tenant farmers, who tend to deplete soils, forests, and water resources more rapidly because they assume or fear they will lose access to them. National Factors Problems at the local level are often reinforced by national policies that neglect or discriminate against the poorer members of society, with negative conse - quences for the environment. For example, tax laws 302 • Developing countries Global Resources may favortherich,or the structureofdevelopmentin - vestment may favor urban areas. Sometimes farmland near cities is taxed at its development value rather than as agricultural land. As a consequence, poor farmers who cannot affordthehigher taxes are forced off the land. In addition, government enactments in- tended to manage common property resources can have negative effects on both the poor and the envi- ronment. For example, in a number of West African countries, colonial and subsequent governments claimed all the trees as their own. Farmers could cut them only after a laborious permit process, and cer- tain species could not be cut at all. While this slowed the process of deforestation, it also dissuaded farmers from planting trees. Recently, this practice has been reversed, and countries such as Burkina Faso, Mali, and Niger are encouraging farmers to mix trees and crops, an ancient farming practice in West Africa. Governments have also been slow to implement adequate land-planning policies and environmental impact assessment. In many Caribbean states, envi- ronmental legislation is fragmented into several dis- parate regulations, and responsibility for its admin- istration is distributed among various departments. As a consequence, developing countries are repeat- ing some of the environmental problems associated with the industrializedcountries,suchasair and water pollution, toxic emissions, and waste disposal prob- lems. Global Factors Global factors combinewithlocalandnational factors to exacerbate unsustainable resource-use patterns. At the global level, developing countries’ options are constrained by a number of interrelated forces, such as declining terms of trade, oppressive debt burdens, and inappropriate investment strategies. These forces have significant consequences for resource consump- tion. With their dependence on primary products, de- veloping countries are often among the losers when trading systems are liberalized. The market prices of primary products have fallen rapidly, while the prices of the manufactured goods that they import have risen significantly. In the effort to make up such finan- cial shortfalls, developing countries may feel forcedto tap their natural resources more extensively. One result of a focus on free trade, with its empha - sis on growth, is the exploitation of natural resources for short-term profit. This exploitation may mean the clearing of rain forests for cattle ranching or the shift - ing of agricultural land from domestic food produc- tion to export crops. In addition, environmental stan- dards and resource regulations can be challenged as barriers to trade. Regulations produced by the North American Free Trade Agreement (NAFTA) and the General Agreement on Tariffs and Trade (GATT) are illustrative. Under NAFTA, each country has to pro- vide other parties with the same access to its resources that it provides to its own citizens and other domestic parties. The Uruguay Round of GATT resulted in some provisions with direct implications for environ- mental regulations. One of GATT’s objectives is to limit most restrictions on trade: Therefore GATT can be used to challenge the rights of nations to use im- port and export controls to conserve threatened re- sources such as forests and fisheries. The new trade provisions also discourage the use of strong environ- mental provisions by states, because these could be judged as being in violation of GATT rules. These reg- ulations work against the concept and practice of sus- tainable use of resources. International institutions, such as the World Bank and the International Monetary Fund (IMF), encour- age export-led development as a priority, but this export-led strategy has reduced many countries’ ca- pacity to address their environmental problems. The World Bank, as the principal single source of funding for Third World development, can have a profound impact on environmental policy in developing coun- tries. Its development model has emphasized large- scale schemes dealing with water management, power generation, and transport infrastructure. Many of these projects have resulted in serious disruptions of local ecosystems, in environmental stress, and in the displacement of thousands of people. The World Bank, and the other multilateral development banks, such as the InterAmerican Development Bank, the Asian Development Bank, and the African Develop- ment Bank, allocate more than one-half of their proj- ect loans to areas that can have marked effects on the environment, including agriculture, rural develop- ment, dams, and irrigation schemes. Oversight of the projects’environmentalconsequencesis inadequate. IMF policy has also had significant environmental consequences for developing countries. The IMF has responded to the Third World debt problem by re- quiring the countries to adopt structural adjustment programs. These programs include a wide range of policy measures intended to restore creditworthiness: Global Resources Developing countries • 303 cuts in government expenditures, reduction or elimi - nation of subsidies, currency devaluation, and reduc- tion of trade barriers. The intent of these programs is to increase foreign exchange earnings so that the countries can make debt payments. However, struc- tural adjustment can have disastrous impacts on the environment. The emphasis on boosting exports to earn foreign exchange can result in the destruction of natural resources such as forests, wetlands, and mangroves and in the excessive development of eco- logically damaging industries such as mining. The pressure for countries to reduce government expen- ditures drastically can cause the elimination or post- ponement of programs to manage wildlife or enforce environmental laws. Additionally, structural adjust- ment programs that hurt the poor will often also hurt the environment: As a last resort, unemployed people might farm fragile hillsides or engage in slash-and- burn agriculture in forest areas. In recent decades, some developingcountrieshave experienced more rapid economic growth than in- dustrialized countries have. In part, their growth re- flects an increasing transfer of basic production to developing countries and the expansion of manufac- turing there. These shifts create additional economic value and employment, but they also increase the en- vironmental burden. Corporations are shifting com- plete industrial operations to the Third World. The end products are then shipped back to the developed country, where consumers get the benefit ofthe prod- uct while shifting the environmental costs of produc- tion to others. For example, there has been a signifi- cant shift of plant investment for organochloride manufacture to the developing world. In the 1980’s and 1990’s, U.S. companies relocated more than two thousand factories to Mexico, where enforcement of environmental laws is minimal. Transnational corporations play a major role in this industrial transition. These corporations are the principal beneficiaries of a liberalized trading system. Because they control the bulk of world trade and in- vestment, they are major environmental actors. They can affect the environment in Third World countries, both directly and indirectly. In order to attract invest- ment from these corporations, a Third World country might adopt inadequate environmental regulations or might choosenot to enforce existing laws. Virtually all commercial enterprises havedirect environmental consequences because of process and product pollu - tion. The former includes pollution generated by the chemical, iron and steel,petroleum, and paper indus - tries. The latter variety is found in agriculture. Because agriculture is the primary economic sec- tor for many developing countries, examining trans- national agribusiness is important. Agribusiness in- terests have made alliances with research institutes, agricultural colleges, regulatory agencies, government ministries, and aid agencies. These relationships en- able them to shape agricultural practices and policies significantly. Their practicesusually reflect a cost-ben- efit analysis that marginalizes environmental costs. Corporate policy can have negative consequences for resources such as land, forests, and water. Transna- tionals control 80 percent of the land used for export crops worldwide. This fact is reflected in land-use pat- terns in countries such as Brazil and India. In Brazil, corporations own more land than is owned by all the peasants combined, and in India, some of the more wealthy farmers grow maizeandsunflowersfor Cargill and tomatoes and potatoes for Pepsi. Corporations specialize in monoculture, with heavy use of chemical fertilizers and pesticides. With the focus on produc- tion for export, developing countries become depen- dent on food imports. This focus has also aided in the destruction of tropical rain forests. More than one- quarter of Central America’s rain forest has been turned to grass for cattle ranching. Almostall the beef raised has been exported. In the 1970’s, beef produc- tion in Latin America attracted more than $10 billion from the World Bank and the InterAmerican Devel- opment Bank. In Africa and Asia, corporations are also at work in the forests, but for timber rather than beef. These activities have meant the destruction of ecosystems and a decrease in biodiversity. Prospects for Sustainable Development Sustainable development was a major agenda item at the 1992 Earth Summit in Rio de Janeiro. Agenda 21, which was adopted at the conference, emphasized sustainable development and the provision of basic needs for the poor. As global awareness of resource limits and environmental damage grow, developing countries are under increasing pressure to adjust rap- idly to environmental circumstances. Developed countries have been the major contributors to com- mon property problems, such as ozone depletion and climate change, but they cannot address these prob- lems adequately without the cooperation of develop - ing countries. As a result, developing countries are be - ing pressed to minimizetheir use of the processes and 304 • Developing countries Global Resources commodities that enriched the industrialized coun - tries. During negotiations over environmental manage- ment regimes, developing countries have been able to bargain for some financial assistance to help them make the transition to more sustainable processes. Still, this small fund will not have a major impact on their transition to a more sustainable consump- tion pattern. Developing countries need to protect their endangered renewable-resource base. Accom- plishing this will require reorienting development to alleviate poverty and enable poor people to meet their basic needs in ways that do not degrade water, soil, and forest resources or reduce biodiversity. This task will be extremely difficult as long as large amounts of their natural resources are owned or controlled by foreign entities. In the present global economic con- text, many developing countries recognize only two viable economic options: exploiting their natural re- sources to the point of exhaustion or importing “dirty industries.” Consequently, the structural inequities that distort global and national societies and econo- mies jeopardize the transition to sustainable develop- ment. If these inequities are not addressed, sustain- able resource use will be an ever-receding mirage. Marian A. L. Miller Further Reading Ascher, William, and Robert Healy. Natural Resource Policymaking in Developing Countries: Environment, Economic Growth, and Income Distribution. Durham, N.C.: Duke University Press, 1990. Barbier, Edward B. Natural Resources and Economic De- velopment. New York: Cambridge University Press, 2005. Bonfiglioli, Angelo. Lands of the Poor: Local Environ- mental Governance and the Decentralized Management of Natural Resources. New York: United Nations Cap- ital Development Fund, 2004. Dellink, Rob B., and Arjan Ruijs, eds. Economics of Pov- erty, Environment, and Natural-Resource Use. New York: Springer, 2008. Durning, Alan Thein. Poverty and the Environment: Re- versing the Downward Spiral. Washington, D.C.: Worldwatch Institute, 1989. Elliott, Jennifer A. An Introduction to Sustainable Devel- opment. 3d ed. New York: Routledge, 2006. French, Hilary F. Costly Tradeoffs: Reconciling Trade and the Environment. Edited by Ed Ayres. Washington, D.C.: Worldwatch Institute, 1993. Gupta, Avijit.EcologyandDevelopment in the Third World. 2d ed. New York: Routledge, 1998. Miller, Marian A. L. The Third World in Global Environ- mental Politics.Boulder, Colo.: Lynne Rienner, 1995. World Bank. Poverty and the Environment: Understand- ing Linkages at the Household Level. Washington, D.C.: World Bank, 2008. Web Site World Resources Institute World Resources 2008: Roots of Resilience— Growing the Wealth of the Poor http://www.wri.org/publication/world-resources- 2008-roots-of-resilience See also: Agenda 21; Brazil; Capitalism and resource exploitation; China; Deforestation; Earth Summit;In- dia; Indonesia; Land ethic; Monoculture agriculture; Population growth; Rain forests; Resources as a source of international conflict; Slash-and-burn agri- culture; South Korea; World Bank; World Commis- sion on Environment and Development. Diamond Category: Mineral and other nonliving resources Diamond is oneofthe world’s most important minerals and gemstones; it is the element carbon (C) crystallized in the isometric system. Background Diamond is the hardest known substance, natural or artificial, and is number 10 on the Mohs hardness scale. The close-packed cubic arrangement of the at- oms gives diamond its unique hardness. It also hasthe highest thermal conductivity of anyknownsubstance. Historical records of diamonds date back to 3000 b.c.e. In recent centuries, Golconda diamonds of India dominated diamond production until the early eighteenth century. In 1725, Brazilian diamond mines gained prominence. South Africa’s “great diamond rush” began in 1867, and in 1890, the De Beers com- pany consolidated dozens of mining communities in Africa. Diamond derives its name from the Greek word adamas, which means “unconquerable.” Almost all of the world’s diamond production comes from Africa, most notably South Africa. Other Global Resources Diamond • 305 diamond-producing countries include Angola, Bor - neo, Ghana, Guyana, Namibia, Sierra Leone, Tanza- nia, Venezuela, Congo, Brazil, and Russia (Siberia). In the United States diamonds have been found inAr- izona, Arkansas, Montana, and Nevada. Technical Definition The atomic number of carbon is 6, and its atomic weight is 12.011. It belongs to Group IVA of the peri- odic table of elements. Gem diamonds have a density of 3.52, although “black diamonds” have a density of about 3.15. Diamond slowly burns to carbon dioxide at a very low temperature (900° Celsius). Diamond’s high refractive index (2.417) and strong dispersion property (0.058) guarantee its su- premacy as a gemstone. However, only about one-fifth of all the diamonds mined qualify as gems. Most of the remaining uncut diamonds are used by industry. Tunnel boring and oil-well drilling equipment uses diamond-studded rotarybits. Carbide grinding wheels, abrasion-resistant cutting tools, and glass-etching and glass-cutting equipment use industrial-quality dia- monds. Some dentists and surgeons use diamond- headed scalpels to cut delicate bones and tissue. Diamond coatings are used in integrated circuits, prosthetic devices, and biosensors. Diamond is the most important industrial abrasive, and industry uses about 80 percent (by weight) of all diamonds pro- duced. However, this represents only about 30 per- cent by value. Creation and Properties of Diamond About 30 meters inside the Earth, exceedingly high pressures and temperatures (more than 1,400° Cel- sius) cause magnesium-rich rock melts to crystallize, resulting in the formation of diamonds. Samples of deep mantle material contain diamonds as a natural component. The reaction of groundwater with hot, magnesium-rich, deep mantle material aided by car- bon dioxide leads to the formation of a rock called kimberlite. Kimberlite is an igneous rock that is ultrabasic and contains very little silica. Kimberlite is the world’s principal source of diamonds. Explosive eruptions create craters filled with deep mantle rock formations and permit diamond-containing rocks to surface through cracks. These are known as dia- mond pipes (sometimes incorrectly called “volcanic necks”). In addition to being the hardest substance, dia- mond is an excellent conductor of heat. Because dia- 306 • Diamond Global Resources Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.Source: Mineral Commodity Summaries, 2009 18,000,000 8,000,000 1,000,000 23,000,000 15,000,000 9,000,000 3,000,000 Carats 25,000,00020,000,00015,000,00010,000,0005,000,000 Congo, Democratic Republic of the China Botswana Australia Russia South Africa Other countries 23,000,000 Industrial Diamonds: World Mine Production, 2008 monds possess the highest thermal conductivity of any known substance, industrial-quality diamonds are used in abrasion-resistant cutting tools. Almostall dia- monds are nonconductors of electricity. However, some diamonds permit the passage of electric current when bombarded with radiation. Diamond crystals form as octahedrons, dodecahedrons, and cubes. A well cut gem can reflect almost all the light that it re- ceives. This quality is called “luster.” In addition, it can disperse or separate the colors of the spectrum while reflecting the incident light. This quality is called “fire.” Occurrence of Diamond Mining experts have discovered hundreds of diamond- containing dikes and pipes in Transvaal, Kimberley District, and Free State (formerly Orange Free State), South Africa; Yakutsk, Siberia; Shinyanga, Tanzania; Mbuji-Mayi, Democratic Republic of the Congo; Yengema, Sierra Leone; Murfreesboro, Arkansas; and several other locations. However, it is not economi- cally feasible to carry out “mine-at-depth” procedures in most of these pipe mines. Unless new pipes are dis- covered, natural diamonds may be exhausted rela- tively soon. The erosion of diamond pipes over millions of years has resulted in secondary deposits called alluvial or placer deposits. These deposits contribute signifi- cantly to the world’s total diamond production. Most alluvial diamonds are recovered from stream gravel, but beach gravel is also a good source. Diamond- containing beach gravel extends to the depths of Global Resources Diamond • 307 These miners, photographed around 1905, and others worked the dozens of South African mines owned by Cecil Rhodes’s De Beers Consoli- dated Mines. Until 1891 the company controlled 90 percent of the world’s diamond production. (Library of Congress) the ocean floor, although there is no economical means of recovering diamonds from ocean depths. Diamonds are also found in glacial tills. Minute quan- tities of microscopic diamonds have been found in meteorites as well. Synthetic Diamonds On February, 15, 1955, the General Electric Company announced its success in creating a synthetic dia- mond. Since then synthetic diamonds have become widely used in grinding wheels and a number of other applications. They are normally single crystals, usu- ally octahedral in shape. Since they have several cut- ting edges, they are preferred over natural diamonds for industrial purposes. To make them, graphite (an- other form of crystalline carbon) is subjected to very high temperatures and pressures. Extreme pressures as high as 296,076 atmospheres (about 30 billion pas - cals) and temperatures as high as 3,037° Celsius (water boils at 100° Celsius) have been used, depending upon the actual process. Two common proce - dures are shock conversion and static conver- sion. Synthetic diamonds are also manufac- tured by the static crystallization of certain alloys and molten metals. Synthetic diamonds, normally black in color, are produced in grain sizes that are about one- hundredths of a centimeter in diameter. It is possible to “grow” larger, gem-quality synthetic diamonds, but the process is too costly to be feasible. Synthetic diamonds are chemically and crystallographically identical to the natu- rally occurring diamond gemstone. “Imitation diamonds,” on the other hand, are completely different from either synthetic or genuine dia- monds. Imitation diamonds do not possess either the hardness or the crystallographic structure of the genuine diamond; they are chemically different. They are made of glass or other material and are simply intended to imi- tate the appearance of a diamond. Cutting Diamond After mining and recovery, gem-quality dia- monds are separated from industrial-quality ones. A rough, uncutdiamond looks like a dull piece of glass. Precise cutting, artful grinding, and skillful polishing of the diamonds yield outstanding gems, and some have attained his- toric fame. Diamond cutting began in India and was later perfected in Italy. Only a diamond can cut a diamond: Diamond crystals are cut, cleaved, shaped, and polished by “diamond dust on a lap.” World-famous diamond cutting establishments are concentrated in Antwerp, Belgium, and in Amster- dam, the Netherlands. India and Israel have also emerged as world leaders in diamond cutting. The most popular cut is the “brilliant cut,” which has a round shape with fifty-eight facets. Gem-quality dia- monds are classified according to their weight, clarity, color, and absence of flaws. The weight of a diamond is measuredincarats;acarat equals 0.2 gram, or about 0.00704 ounce. Transparent, colorless, and light blue diamonds are extremely rare and are considered to be highly valuable gems.There are red, pink, blue, and green diamonds. Diamonds with a yellow tint are more common. As the tint becomes increasingly yellowish, the value decreases. Industrial-quality diamonds are gray, brown, or black and are almost opaque. They are gems of poor quality. 308 • Diamond Global Resources Machinery manufacturing 32% Mineral exploration 18% Stone & ceramic production 22.5% Construction 14.5% Transportation 8.5% Other 4.5% Source: Historical Statistics for Mineral and Material Commodities in the United States U.S. Geological Survey, 2005, industrial diamond statistics, in T. D. Kelly and G. R. Matos, comps., ,U.S. Geological Survey Data Series 140. Available online at http://pubs.usgs.gov/ds/2005/140/. U.S. End Uses of Industrial Diamond Famous Diamonds The largest diamond ever found, the Cullinan, was found in 1905 in the Premier Mine, Transvaal, South Africa, and weighed 3,106 carats. This stone was cut and polished into several gems, two of them world fa- mous: The 530-carat Star of Africa and the 309-carat Star of Africa II are among the British crown jewels, housed in the Tower of London. These are the world’s largest cut diamonds. The cutting of the Cullinan also resulted in another seven large gems and ninety smaller ones. The 109-carat Koh-i-Noor (“mountain of light”), set in the British crown itself, is the oldest diamond gemstone known to historians; its history has been traced back to 1304. This diamond had its origin in In- dia, and it originally weighed 186 carats before Queen Victoria had it recut in 1852. Many believe that the largest blue diamond, the 44.5-carat Hope diamond, presently in the Smithsonian Institution, adorned the eye of an Indian god. Other world-famous dia- monds India has contributed include the Regent or Pitt (140 carats, presently in the Louvre, France); the Orlov (200 carats, presently in Russia); the Florentine (137 carats, location unknown); and the Great Mogul (280 carats, location also unknown). Mysore Narayanan Further Reading Balfour, Ian. Famous Diamonds. 4th ed. London: Chris- tie’s, 2000. Chatterjee, Kaulir Kisor. “Diamond.” In Uses of Indus- trial Minerals, Rocks, and Freshwater. New York: Nova Science, 2009. Green, Timothy. The World of Diamonds. New York: Morrow, 1981. Hart, Matthew. Diamond: A Journey to the Heart of an Ob- session. New York: Walker, 2001. Hazen, Robert M. The Diamond Makers. New York: Cambridge University Press, 1999. Maillard, Robert, Ronne Peltsman, and Neil Grant, eds. Diamonds, Myth, Magic, andReality. New rev. ed. New York: Bonanza Books, 1984. Nazaré, M. H., and A. J. Neves, eds. Properties, Growth, and Applications of Diamond. London: IEE, 2001. O’Donaghue, Michael. Gems: Their Sources, Descrip- tions, and Identification. 6th ed. Oxford, England: Butterworth-Heinemann, 2006. Prelas, Mark A., Galina Popovici, and Louis K. Bige - low, eds. Handbook of Industrial Diamonds and Dia - mond Films. New York: Marcel Dekker, 1998. Zoellner, Tom. The Heartless Stone: A Journey Through the World of Diamonds, Deceit, and Desire. New York: St. Martin’s Press, 2006. Web Sites American Museum of Natural History The Nature of Diamonds http://www.amnh.org/exhibitions/diamonds 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 Industrial Diamonds: Statistics and Information http://minerals.usgs.gov/minerals/pubs/ commodity/diamond See also: Abrasives; Carbon; Gems; Graphite; Mohs hardness scale; Rhodes, Cecil. Diatomite Category: Mineral and other nonliving resources Where Found Diatomite is found in deposits near present-day or an- cient bodies of water, becauseit is composed of the sil- ica shells of water-dwelling diatoms. Diatomite depos- its are found throughout the world; major producers include the United States, China, Denmark, and Ja- pan. The United States is the main producer of diato- mite, accounting for at least 50 percent of the world’s diatom exports every year. Primary Uses Uses for diatomite fall into four main categories: forfil- tering, for insulating and building, as a filler material, and as amild abrasive. Diatomite is commonly used to filter a wide variety of substances, ranging from oils to drinking water. As an abrasive, itis used in toothpastes and metal polishes. Many products, ranging from ce- ramics topaints,usediatomite as a fillertoaddvolume. Technical Definition Chemically, diatomite consists primarily of silica with trace amounts of magnesium, sodium, iron, and Global Resources Diatomite • 309 . ex- amples of resource problems in desert areas include overhunting of native ungulates for animal products such as tusks. Natural Resources Deserts of the world hold most of the reserves of oil, natural. use of natural resources to be feasible, people needtohavesomemeasure ofcon- trol of, and access to, resources. Case studies indicate that small holders who own their land tend to take care of. 2008. Web Site World Resources Institute World Resources 2008: Roots of Resilience— Growing the Wealth of the Poor http://www.wri.org/publication/world -resources- 2008-roots -of- resilience See also: