Earlham Physical Geology, Fall 2005

photocourtesy of ABC Rural

Bauxite was first discovered in 1821 by Pierre Berthier in Les Baux, France. It is named for named for Les Baux and was once known as beauxite.


Related Links

Bauxite Museum


Bauxite Teeth

Photo courtesy Arkansas Roadside Travelouge


View an interactive map of bauxite deposits








Bauxite loading Jetty in Weipa, Australia

Copyright © 1997, 1998, 1999, 2000 & 2001 Lighthouse Computer Training & Development
Copyright © 2002, 2003, 2004 & 2005 Lighthouses of Australia Incorporated

Image by Winsome Bonham courtesy of Lighthouses of Australia, Inc.

The largest bauxite mine in the world is located in Weipa, Australia. In 1955 geologist Henry Evans realized that the red cliffs in the area were composed of pure bauxite. The mining town of Weipa was built by Comalco and the state government shortly afterwards in order to exploit this area.


Bauxite Mining facilities in Alcan Gove, Arnhem Land, Australia

Bauxite crusher

19 Kilometer conveyor belt takes the bauxite to be processed into alumina.

Photos courtesy of ABC Rural



Photo courtesy Prof. Robert Lancashire, Dept. of Chemistry, University of the West Indies

Bayer Plant in Jamacia



Photo courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenny/

Bauxite crusher at Nhunbuy

Bauxite converyor at Nhulunbuy, Australia. Photo courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenn

Bauxite Conveyor at Nuhunbuy


photo courtesty Global Alumina

Pipeline in Guinea, Africa.












photo courtesty Global Alumina

Pipeline in Guinea, Africa

photo courtesty Global Alumina

Reclamation Area, Guinea, Africa.



Yolngu Women

















Transcript of Petition




Bauxite is a naturally occuring heterogenous material.

Bauxite photo Courtesy Minerals in Your World! and Pisolitic bauxite photocourtesy of ABC Rural

Bauxite is sometimes thought be a mineral, but it is actually a rock. Bauxite is the primary ore of aluminum. It is formed in tropical climates as the result of chemical weathering; the leaching of silica in aluminum-bearing rocks. It consists of one or more of three aluminum hydroxides minerals, gibbsite, bohmite, diaspore, in varying proportions. Gibbisite is true aluminum hydroxide while bohmite and diaspore are aluminum-oxide hydroxides. Diaspore differs from bohmite in its crystalline structure and necessitates higher temperatures for rapid dehydration. Bauxite also contains varying amounts of iron oxide, silicon oxide, titanium, and small amounts of clay and other silicates.

Bauxite can be very hard, but is generally fairly soft and clay-like. It comes in a few different colors, including, brown, tan, yellow, red, white and various combinations. More often than not it has something of a reddish tint to it according to amount of iron oxide present. Bauxite exists in three forms: loose pisolitic, with small and rounded marble-size grains, cemented pisolitic, with small grains are cemented together, and tubular, larger chunks with erratic cavities. (Mineral Information Institute, USGS, 2005, World-Aluminum, 2000.)

Areas with Bauxite
Bauxite is found predominantly in tropical and subtropical areas near the equator, but there are some regions in Europe that contain bauxite, and there was once a great deal of bauxite in Arkansas. Major deposits can be found in the Caribbean and Mediterranean regions. Australia has the 40% of the world’s bauxite, followed by New Guinea and then Jamaica. (World-Aluminum, 2000)

Bauxite Deposits
Bauxite is found in four different types of deposits, blanket, pocket, interlayered, and detrital.

Blanket deposits are flat layers of bauxite, on average four to six meters thick, but can be anywhere from one meter to forty meters thick. They occur close to the surface and can be many kilometers long. Blanket deposits primarily occur in West Africa, Australia, South America and India.
Pocket deposits, as the name would imply, are pockets of bauxite in the ground, ranging from less than one to thirty meters deep. They can be found as isolated or as overlapping deposits. Pocket deposits are found in Jamaica, Hispaniola, and Southern Europe. Interlayered deposits were once existed as other types of rocks, but over time have been covered and packed down. They are then more compressed than the other types of deposits. Interlayered deposits occur in America, Suriname, Brazil Guyana, Russia, China, Hungary and the Mediterranean.
Detrital deposits are not very common. Detrital deposits form when bauxite from another type of deposit erodes and builds up elsewhere. The only substantial detritial deposit was located in Arkansas. (Mineral Information Institute, World-Aluminum, 2000.)


Bauxite Mining

Bauxite mining in Nhulunbuy, Australia. Photo courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenny/

One hundred million tons of bauxite are mined each year. Bauxite very easily mined and processed. It generally requires no drilling or blasting because of its relative softness. Bauxite predominantly exists naturally in an acceptable grade, unlike many other metal ores. Enhancing unacceptable grade bauxite by removing clay is also an easy and cheap process. As 80% of the world’s bauxite is gathered from blanket deposits, which are relatively shallow, surface mining is used. The remaining 20% comes from underground pocket deposits located in Southern Europe and Hungary, which require more destructive and problematic excavation techniques.

Bauxite mining in Nhulunbuy, Australia. Photos courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenny/


Alumina and Aluminum Production

Aluminum is the second most used metal in the world. Call for aluminum is high as it suited for many purposes. It is a strong, resilient and lightweight material able to conduct heat well. Many materials in everyday life are made from aluminum, and most materials used for transportation are made from aluminum. Cars, trucks, boats, aircrafts, and high voltage power lines are contain aluminum. Aluminum is also easily recycled, and loses none of its quality in the recycling process. About 85% of the world's bauxite goes to make alumina, to then create aluminum, the remaining percentage is used to create chemcial, abrasive and refractory products. (Mineral Information Institute, " date unknown)

Bayer Process

The Bayer process is the manner in which bauxite is converted into alumina. Alumina is anhydrous aluminum oxide, a fine white powder. Alumina is a valuble commodity because from alumina one can produce aluminum; 90% of the world’s alumina goes to produce aluminum. The Bayer Process was developed in 1888 by Karl Joseph Bayer. The process was relatively cheap, and caused a substantial boost in aluminum production, making it an everyday commodity. Today the Bayer process is still the most inexpensive method.

Photo courtesy Prof. Robert Lancashire, Dept. of Chemistry, University of the West Indies

First the bauxite is crushed to make the grain size relatively uniform. It is then mixed with caustic sodium hydroxide, at high temperatures and pressures. It is then grinded to an even finer grain. A discharged slurry called red mud, composed of sodium aluminate and residues of undissolved iron, silicon and titanium that sink to the bottom of the tank and are removed. The slurry then enters a digester where more caustic sodium hydroxide is added, and the results are heated to 300 degrees Fahrenheit. This produces a sodium aluminate solution. Before going to settling tanks, the solution is pumped into flash tanks which decrease the temperature and pressure. In the settling tanks impurities that don’t dissolve, such as sand, iron and other trace elements, separate and settle to the bottom. The liquid at the top goes through another series of filters, where it is washed to recover alumina and sodium hydroxide, and the remaining red mud is stored in storage ponds and dried by evaporation. This liquor is then pumped into giant cloth filters over steel frames, called “leaves.” The solid impurities caught in these filters, none as filter cake, and are washed to remove the caustic soda and alumina. The remaining liquid, a sodium aluminate solution, is then pumped to precipitators. Aluminum hydrate is then added in order to initiate the precipitation of pure alumina; the aluminum hydrates seeds enable alumina crystals to grow around them. These crystals sink to the bottom of the tank and are pumped to thickening tanks, filtered again, and then move by conveyor to calcination kilns. The calcination kilns are rotating and brick lined. They reach up to 2,000 degrees Fahrenheit and remove the combined water from the alumina hydrate. The kilns are tilted so as to allow move down to the cooling equipment. This process creates a white alumina powder. At the end of the process the leftover sodium hydroxide can be used again. (Rocks and Minerals.com, 1999, Lancashire, 1982.)


Hall-Heroult Process
The Hall Heroult Process is an industrial electrolytic process used to extract aluminum from alumina. The process was arrived at by Charles Hall in the United States and Paul L.T. Heroult of France, simultaneously. The process requires extremely high temperatures and huge amounts of electricity, often necessitating the presence of hydroelectric plant. It the chemical reaction between molten cryoline, or sodium aluminum fluoride material and alumina creates aluminum. It takes four to six tons of bauxite to produce one tone of aluminum metal.

Copied by permission from the "Electrochemistry Encyclopedia" (http://electrochem.cwru.edu/ed/encycl/) on December 4, 2005. The original material is subject to periodical changes and updates.

The process takes place in carbon-lined steel containers and uses the DC, direct current. The average voltage is 5.25 volts and the amperage is high,100,000 to 150,000 amperes. The current flows between a positively charged anode composed of petroleum cake and pitch, and a negatively charged cathode, created by the carbon container. The reaction between the carbon and the oxygen of the alumina produces carbon dioxide and metallic aluminum are produced. Aluminum settles to the bottom and pumped out. (Rocks and Minerals.com, 1999, Lancashire, 1982, Beck, 2001.)


Mining Pollution and Rehabilitation
Mining is devastating to the environment. Jamaica, for example, has lost much of its forests to mining; 75% of original forest cover in Jamaica. Before a company begins to mine an area for bauxite, the land must be cleared of all vegetation and a minimum of 6 inches of topsoil, topsoil which is nutrient and seed bearing. Companies also often build roads to the mine, causing further damage. Mining causes speedy soil erosion, dry up rivers and streams. This wound to the ecosystem can have a devastating effect on animal life in the area. Additionally the processing bauxite to create alumina and aluminum is very environmentally distressing. The red mud if improperly disposed of can cause seep into groundwater, contaminating the water supply in an area. Frequently tailings piles are disposed of close to the plant, and can be eroded by wind and water and seep into the ground. Damaged pipes in any step of the process can spoil arable land. There are also air pollutants such as dust and noxious chemicals that arise from the calcination process. The Halls-Heroult process produces fluoride emissions which can cause skeletal disorders and fluorosis. These aluminum creating processes produce sulfur and nitrogen dioxide which can not only make for an exceedingly unsafe working environment, but also create acid rain.

There are not infinite amounts of bauxite in an area and thus mining is a temporary process. Once an area has been mined it is possible to restore it to some degree. When an area is ready to be rehabilitated, overburden is first removed from the pit floor, and topsoil returned. The mining process, however, reduces the water retention ability of soil, and so even when the topsoil is replaced it is less able to retain water. Many times rehabilitation efforts cannot restore the total former diversity of plant and animal life. Great strides, however, can be made. Past mining operations, predating environmental laws, have devastated many environments, betraying a lack of scientific knowledge and great carelessness. There are a great number of abandoned mines. But today, nearly all mining companies have a rehabilitation plan before they begin to mine. Additionally most mining companies attempt to preserve topsoil, so they can return it when the area is done being mined, and many have their own nursery facilities. (Bergland, Johanson, 2004, International Council on Mining and Minerals, 2005, World Aluminum, 2000, Nichols and Nichols, 2003,The European Aluminum Association, Azom.com, date unknown, Gardner, date unknown)

Social Impact

Because bauxite mines can be so disruptive to the environment, and also causes large amounts of noise pollution, it is not surprising that many people wouldn't want a bauxite mine in their area. But there are also additional reasons why people have fought to prevent mining. In many of the areas where bauxite is found, there is a history of oppression. In Jamacia, Africa and Australia exploitaton of land and people have become major issues. When bauxite was discovered on sacred Aboriginal land in Australia, for example, it caused great controversy over land rights. But because bauxite mines make money and are economically benefical, their social and religious injuries tend to be overlooked.

Yirrkala Bark Petition 1963
Land is vastly important to Aboriginal people and it tied tightly to all aspects of Aboriginal life. Land is central to the Aboriginal concept of the Dreaming. In the Dreaming, a time before time, the Aboriginal people believe that their ancestors walked the earth, in different forms, giving shape to the landscape, creating sacred objects and cementing rituals and customs, which are the foundation for Aboriginal religious, political and social life.

Photo courtesy enair.org

When Europeans first arrived on the shores of Australia they declared the land to be terra nullius, a land of nothing. The Indigenous inhabitants had no rights whatsoever under that concept law, and in most areas were abused and exploited by white settlers, forced into missionary systems and separated from their families. In the remote area of Yolngu in northeastern Arnhem Land, however, although a European mission was established, the Yolngu people had not been “conquered,” and lived in relative peace with the Europeans. In 1960s, however, the Yolngu people discovered French prospectors on their land, who wanted to exploit the bauxite deposits in the area. But under the law of terra nullius, the Aboriginal people had no say in stopping them. In 1963 they petitioned the House of Representatives in Canberra. The petition, written in Gumatj, one of the Yolngu languages as well as English uses their own cultural language of symbols and tradition of bark painting. There a two petitions, one for each of the two Dhuwa and Yirritja moieties. The white government, however, let the company mine the bauxite. The Yolngu took them to court in 1968 and lost. But eventually gained ground with the Aboriginal Land Rights (Northern Territory) Act of 1976, which gave them ownership and land title to lands reserved for them. And the bark petition did succeed in garnering national attention and forcing the white government to recognize the Aboriginal people on their own cultural terms. (Morphy,1998)

Photo courtesy enair.org

Literature Cited

USGS, "Bauxite and Alumina Statistics and Information," September 23, 2005.

International Council on Mining and Minerals, "Reforesting After a Bauxite Mine," 2005.

Berglund, Christie, Johanson, Tommy, "Jamaican Deforestation and Bauxite Mining--The Role of Negotiations for Sustainable Resource Use," Minerals & Energy, September 2004, Vol 19 Issue 3, p. 2-14.

Nichols, Owen G., Nichols, Flora M., Restoration Ecology
"Long Term Trends in Faunal Recolonization After Bauxite Mining in the
Jarrah Forest of Southwestern Australia," September 2003, Vol. 11 Issue 3, p. 261-272.

Beck, Theodore, Electrochemistry Encyclopedia, "Electrolytic Production of Aluminum," October 2001 http://electrochem.cwru.edu/ed/encycl/art-a01-al-prod.htm

World-Aluminum, "Bauxite Mine Rehabilitation", and "Bauxite Geology," 2000.

Rocks and Minerals.com, "How Aluminum is Produced," May 16, 1999.

Morphy, Howard, Aboriginal Art London: Phaidon Press, 1998

Prof. Robert Lancashire, Dept. of Chemistry, University of the West Indies, "The Chemistry of Processing Jamaican Bauxite," 1982.

The European Aluminum Association, Azom.com, "Bauxite Mining and the Environment," date unknown,

FAO Document Repository, Gardner, John, "Rehabilitating Mines to Meet Land Use Objectives: Bauxite
mining in the Jarrah Forest of Western Australia," date uknown.

Mineral Information Institute, "Aluminum and Bauxite," date unknown.

Young, B.S., "Jamacia's Bauxite and Aluminum Insdustries," Annals of the Association of American Geographers, September 65, Vol 55, Issue 3, p. 449-464.








Author: Caitlin Lamb
Creation/revision date: December 6, 2005

Link to other Student Webpages for 2005 Fall Earlham Physical Geology

This website was prepared as an assignment for Geosciences 211 (Physical Geology) taught in the Fall semester, 2005 at Earlham College, Richmond, Indiana.

Earlham College Geosciences Department Earlham Geosciences 211: Physical Geology

Copyright 2005 Earlham College. Revised December 6, 2005 . Send corrections or comments to lambca@earlham.edu