The coal-bearing strata of Argentina, Bolivia, and Chile crop out along the flanks of the Andes Mountains. Carboniferous coals are known in Argentina from the provinces of San Juan, Mendoza, Neuquén, and Chubut. The Middle and Upper Carboniferous coals are anthracite. Permian coals are known from the provinces of Córdoba, San Juan, Mendoza, and Chubut in Argentina; from the vicinity of Lake Titicaca in Bolivia; and from La Ternera and Quilacoya in Chile. The Permian coals also are anthracites. However, numerous faults and folds, a high ash content, and the limited extent of the coal-bearing basins make these Paleozoic coals of little economic interest. The same is true of the Mesozoic coals that are known from Argentina in the provinces of San Juan, Mendoza, and Neuquén. The only important and commercial coal deposits from this three-country region are Tertiary coals in Argentina and Chile. In Chile the proved and probable bituminous coal resources total about 100 million metric tons, most of which is in the Eocene Arauco basin, which contains the best-quality coal in Chile. The calorific value of the best of this coal is 13,500 Btu/lb. The Oligocene subbituminous coals of the Magallanes basin in Chile are considered to be one of the largest reserves in South America — calculated to be 5,400 million metric tons. This is in addition to the 380 million metric tons of reserve in the Argentine Río Turbio coal deposits. The Magallanes and Río Turbio coals have a high ash content and a calorific value of 8,500 Btu/lb.

In general, the coal deposits of Argentina fall into four groups on the basis of their predominant geologic ages: Neogene, early Tertiary, Jurassic, and Triassic. These four groups are related to the tectonic and stratigraphic framework of the country. Neogene coals are mainly allochthonous lignitic coals of limnic origin; they have large amounts of ash. Predominating in the deposits of early Tertiary age are subbituminous, high-volatile coals of both limnic and paralic origins, locally with some coking properties. The Jurassic and Triassic provinces have bituminous coals with agglomerating and coking properties. The Jurassic coals were deposited mainly in a paralic environment; the Triassic coal-bearing strata mainly represent a limnic environment. A total reserve of 483,921,000 metric tons is estimated on the basis of very scanty data. Only the Paleogene Río Turbio and Pico Quemado deposits of southern Argentina have been studied in some detail. The coal-bearing early Tertiary Río Turbio deposit contains 99 percent of Argentina’s established reserve. Increased study of the Argentine coals will be pursued as a result of the world energy crisis. It is hoped that much larger reserves than those currently known will be established. During 1974, a total of 625,647 metric tons was produced, and it is hoped that production will be increased to 3,000,000 metric tons peryear.

Brazil has five coal-bearing regions: (1) Pliocene(?) coal in the Pébas Formation of the Upper Amazon basin; (2) Eopaleozoic coal in the Rio Fresco Formation of the Rio Fresco region; (3) Pennsylvanian coal in the Piauí Formation of the Tocantins-Araguaia region, western Parnaíba basin; (4) Mississippian coal in the Poti Formation, eastern Parnaíba basin; and (5) Late Carboniferous or Early Permian coal in the Paraná basin. The Paraná basin contains all of the country’s commercial coal, which is in the Rio Bonito Formation of the Gondwana sequence. Total blocked reserves are 3.2 billion metric tons, of which about 5.6 million tons of run-of-mine coal is extracted annually.

The coal deposits of Peru are in three facies of the Lower Cretaceous Goyllarisquizga Group — the eastern, southern, and western facies. Only the western facies is divided into formations, which are from bottom to top the Oyón, Chimú, Santa, Carhuaz, and Farrat. The most important coalfields are the Goyllarisquizga, Jatunhuasi, Oyón, and the “Northern Anthracite” fields. The Goyllarisquizga field, in constant production since 1903, has yielded at least 8,800,000 metric tons of bituminous coal, which has been used to make metallurgical coke for the Cerro de Pasco Corporation’s smelter in La Oroya. The coal produced in 1967 averaged 54.0 percent ash, 21.5 percent volatile matter, and 21.5 percent fixed carbon. The Jatunhuasi field is a long, narrow body of coal east of the continental divide. It has been explored by the Cerro de Pasco Corporation—now Empresa Minera del Centro del Perú (Centromin) — because it constitutes the company’s main source of supply with a resource potential of about 8 million metric tons, although proved reserves are considerably less. The coal beds exhibit characteristics different from those in the Goyllarisquizga field, and the ash content is in general lower than that for coal in the Goyllarisquizga field. In the Oyón basin both anthracite and bituminous coals occur n i the Oyón Formation. Variations in rank of the coals are either the result of intrusion of granodiorite stocks or of intense tectonic activity during which most of the coal was sheared and shattered. The coal in northern Peru is of anthracitic rank. The coal-bearing rocks in this area extend from the Santa River valley to the upper Chicama River. Coal beds occur in both the Chimú and Farrat Formations. By far the most important area is the region of the upper Chicama, where a substantial tonnage could be developed if a suitable market could be found.

The coal deposits of southern Ecuador are in remnants of Tertiary basins now perched in topographic basins at elevations of 2,000 to 3,000 m. Recent mapping suggests that undisturbed coal beds may underlie broad areas, but they will remain untouched because the cover is thick. The known seams, exposed in narrow faulted belts, are steep, disrupted, and shattered. They are as thick as 5 m and contain mostly subbituminous coal and lignite, but have objectional amounts of shale, bentonite, and pyrite. Reserves in the exposed seams of the Malacatus and Loja basins are said to be roughly 1 million metric tons each; in the Cañar-Azuay basin, the reserves are said to be roughly 20 million metric tons. Little of this can be considered economically mineable, however, because an attempt at semimechanized underground mining was unsuccessful. Subterranean gasification may be required.

Colombian coal deposits range in age from Maestrichtian-Paleocene in the Sabana de Bogotá and Boyacá basins to middle Oligocene in the Amagá-Titiribí basin in Antioquia. On the basis of age alone, these coal beds should be of lignitic rank, but because of the intense Andean tectonism (especially during Pliocene time) the rank has been increased to bituminous coal with high to medium volatile-matter content. In some areas, as a result of thermometa-morphic action by the intrusion of porphyritic andesite, the coal beds have been transformed to meta-anthracite. Chemical analyses of the best known coal deposits show a large range in rank. The main basins studied are Amagá-Titiribí (middle Oligo-cene), Santander (Paleocene-Oligocene), Valle del Cauca (Eocene), Cerrejón and Jagua de Ibirico (Paleocene), and Boyacá-Sabana de Bogotá (Maestrichtian-Paleocene). Evaluations made in Colombia in 1968 were 5 billion metric tons of exploitable coal, of which 5 percent is measured coal, 15 percent is indicated coal, and 80 percent is inferred coal. There are some basins yet to be explored and evaluated; when this is accomplished, total coal resources in Columbia may be as much as 10 billion metric tons.

Commercial coal deposits ranging in rank from lignite to anthracite are present in Argentina, Brazil, Chile, Colombia, Mexico, Peru, and Venezuela. Some of the bituminous coal is weakly coking. The commercial deposits are of Triassic, Jurassic, Cretaceous, and Tertiary ages, except those in Brazil, which are of Pennsylvanian and Permian ages. Most coal beds are less than 3 m thick, but some are as much as 5 to 8 m thick. Much of the coal in Brazil and Mexico occurs in flat-lying or gently dipping rocks. In the other countries, the coal beds commonly are folded and faulted and at places are intruded by igneous rocks associated with the Andean uplift. Rough estimates based on available data indicate that the largest coal resources, about 10 billion metric tons, are in Columbia. Resources in Brazil, Venezuela, Mexico, and Chile are estimated at more than 1 billion metric tons for each country, and in Argentina and Peru, resources amount to more than 250 million metric tons for each country. Detailed geologic investigations are needed to provide a basis for more meaningful estimates. During 1973, Brazil, Chile, Colombia, and Mexico each produced more than 3 million metric tons, dominantly of bituminous coal. Imported coal consisted almost entirely of low-volatile bituminous coal, which was blended with domestic coal to manufacture coke. Very little coal was exported.

A review of the available information on carbonaceous sedimentary rocks in the republics of Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama reveals the presence of coal and lignite beds, but no commercial production has been developed in any of these countries. The oldest coal beds, with thicknesses up to 2.5 m, crop out in central Honduras in at least six localities. They are interbeds in the argillaceous Triassic-Jurassic(?) El Plan Formation. This unit is strongly folded and faulted and in some places is intruded by dioritic plutons. The outcrops—in Yoro Department, Honduras—appear to be less deformed. In west-central Guatemala, near the border with Chiapas State, Mexico, coal beds are reported that possibly are correlatable with the El Plan Formation. Thin lignite beds in Cretaceous carbonate rocks in Guatemala do not seem to be important. In Panama, Costa Rica, and Guatemala, many different lignite beds, some more than 1 m thick, are reported in argillaceous and sandy Miocene strata. In Panama, these lignite beds occur in the Gatún Formation, whereas in the Izabal region of Guatemala, they are associated with beds of Miocene to Pliocene age. In most places, these Tertiary rocks are folded and faulted. They were evaluated in Izabal by a private mining company in 1968. Associated with sedimentary rocks of volcanic origin and probably of Pliocene to Pleistocene age, many thin lignite beds of local extent are found in intermontane basins of the volcanic provinces of the Central American countries. Only a few localities could attain importance for mining for local consumption.

Most of the coal in Mexico is concentrated in three widely separated regions Coahuila on the northeast, Sonora on the northwest, and Oaxaca on the south-southeast. In the Coahuila region, bituminous coking coals are present in Upper Cretaceous rocks. The Sonora region contains deposits of Upper Triassic anthracitic coal, altered by probable thermal metamorphism. The Oaxaca region contains anthracitic and some bituminous coking coal in Lower(?) to Middle Jurassic sequences. Through 1973, only the coal deposits of the Coahuila region had been developed commercially. The coals of the Sonora and Oaxaca regions are undeveloped because of unfavorable geo-economic conditions and lack of exploration. Through 1973, the Coahuila region had yielded about 110 million metric tons of coal, most of which was used to produce coke. Present production is 4,250,000 metric tons per year. The largest mines include one underground mine (Sabinas no. 2) and one openpit mine (La Florida), which produce 40,000 metric tons per month. Only reconnaissance-geologic investigations, complemented locally by a few limited drilling projects, have been made in the Sonora and Oaxaca regions. Exploration has been more extensive in the Coahuila region. There are many totally unexplored areas with potential coal resources. The estimated resources in the Sabinas area of the Coahuila region total 1,781 million metric tons classed as reserves in situ, and 1,180 million metric tons classed as potential but not commercially important at present. North of the Sabinas area, in the Río Escondido basin, the estimated resources total 120 million metric tons classed as measured. In the Sonora region the estimated resources total 11 million metric tons classed as reserves in situ for the Santa Clara coalfield and 4 million metric tons classed as measured, 9 million metric tons classed as inferred, and 18 million metric tons classed as possible for the San Marcial district. In the Mixtepec and Tezoatlán coal fields of the Oaxaca region, the estimated resources total 24 million metric tons classed as inferred and 26 million metric tons classed as possible.

The remote location of most United States lignite deposits with respect to major markets and the relatively low calorific value of lignite have prevented, until recently, any significant growth in demand. Unprecedented demands for electric power and recent innovations in its transmission now enable lignite to share with other coals in this growth market. This is particularly true as oil and natural gas resources in the United States decrease and become more difficult to find. Whereas the total reported shipments of lignite had fluctuated between 2.9 and 4.4 million short tons in the decade before 1968, shipments by 1975 had increased significantly to about 19.8 million short tons. The 1975 figure, however, reflects the production of Texas, which was not included in the data for 1956–1968. In 1975, approximately 4.2 million short tons of U.S. lignite was consumed annually in markets other than electricity—for example, in residential, commercial, and industrial establishments and as a raw material for producing barbeque briquettes, montan wax, and activated char. Although not economically feasible at this time, processes have been developed in which lignite also can be used for the production of chemicals, high-Btu gases, liquid fuels, fertilizers, specialty carbons, and as a reductant for preparation of taconite pellets. Reserves of lignite are adequate to meet substantial increases in demand, and the costs of recovering the reserves are among the lowest in the United States compared to the costs of recovering reserves of other types of energy. In the immediate future, additional demand for lignite will depend essentially on its increased use to generate electric power. In the long range, nuclear power may limit increases in demand for lignite for power generation. Growth in the utilization of lignite may then depend on the development of the new markets or new products from lignite, such as synthetic fuels. The present United States oil and natural gas shortage also will increase the demand for lignite.