Trona (trisodium hydrogendicarbonate

dihydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

, also sodium sesquicarbonate dihydrate, Na₂CO₃·NaHCO₃·2H₂O) is a non- marine

evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

. It is mined as the primary source of

sodium carbonate Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...

in the United States, where it has replaced the

Solvay process The Solvay process or ammonia–soda process is the major industrial process for the production of sodium carbonate (soda ash, Na2CO3). The ammonia–soda process was developed into its modern form by the Belgian chemist Ernest Solvay during the ...

used in most of the rest of the world for sodium carbonate production. Turkey is also a major producer.

Etymology

The word entered English by way of either Swedish () or Spanish (), with both possible sources having the same meaning as in English: the mineral

natron Natron is a naturally occurring mixture of sodium carbonate decahydrate ( Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and sodium sulfate. ...

from North Africa. Both the Spanish and Swedish terms derive from the Arabic ''trōn'', which in turn derives from Arabic ''natron'' and Hebrew (''natruna''), which comes from

ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

(''nitron''), derived ultimately from

ancient Egyptian Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...

''ntry'' (or ''nitry'’).

Natural deposits

Trona is found at Owens Lake and

Searles Lake Searles Lake is an Endorheic basin, endorheic dry lake in the Searles Valley of the Mojave Desert, in northwestern San Bernardino County, California. The lake in the past was also called Slate Range Lake and Borax Lake. The mining community of ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

; the

Green River Formation The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River (Colorado River), Green River in Colorado, Wyoming, and Utah. The sedimen ...

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

and

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

; the Makgadikgadi Pans in

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

and in the

Nile Valley The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the longest river i ...

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

. The trona near

Green River, Wyoming Green River is a city in and the county seat of Sweetwater County, Wyoming, United States, in the southwestern part of the state. The population was 11,825 at the 2020 census. It is the 7th most populous city in Wyoming. History The townsi ...

, is the largest known deposit in the world and lies in layered

deposits below ground, where the trona was deposited in a lake during the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

Period.Wyoming Mining Association (2017)
Wyoming Mining Association: Trona Mining
Wyoming Mining Association. Retrieved on 2017-10-25. Trona has also been mined at Lake Magadi in the Kenyan Rift Valley for nearly 100 years. The northern part of

Lake Natron Lake Natron is a salt lake, salt or soda lake, alkaline lake located in north Ngorongoro District of Arusha Region in Tanzania with its far northern end crossing into Kenya. It is in the Gregory Rift, which is the eastern branch of the East A ...

is covered by a 1.5 m thick trona bed, and occurs in 'salt' pans in the

Etosha National Park Etosha National Park is a national park in northwestern Namibia and one of the largest national parks in Africa. It was proclaimed a game reserve in March 1907 in Ordinance 88 by the Governor of German South West Africa, Friedrich von Lindequist. ...

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

. The Beypazari region in the

Ankara Province Ankara Province (, ) is a province and metropolitan municipality of Turkey with the capital city Ankara. Its area is 25,632 km2, and its population is 5,782,285 (2022). History The site of the modern city has been home to settlements ...

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

has some 33 trona beds in two fault-bound lensoid bodies in and above

oil shale Oil shale is an organic-rich Granularity, fine-grained sedimentary rock containing kerogen (a solid mixture of Organic compound, organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general compos ...

s of the Lower Hirka Formation (16 in the lower and 17 in the upper body). The Wucheng basin trona mine,

Henan Province Henan; alternatively Honan is a province in Central China. Henan is home to many heritage sites, including Yinxu, the ruins of the final capital of the Shang dynasty () and the Shaolin Temple. Four of the historical capitals of China, Luo ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

has some 36 trona beds (693–974 m deep), the lower 15 beds are 0.5–1.5 m thick, thickest 2.38 m; the upper 21 beds are 1–3 m thick, with a maximum of 4.56 m hosted and underlain by dolomitic oil shales of the Wulidui Formation. Trona has also been found in

magmatic Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

environments. Research has shown that trona can be formed by auto

metasomatic Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is traditionally defined as metamorphism which involves a change in the chemical com ...

reactions of late-magmatic fluids or melts (or

supercritical fluid A supercritical fluid (SCF) is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous sol ...

-melt mixtures), with earlier crystallized rocks within the same plutonic complex, or by large-scale

vapor In physics, a vapor (American English) or vapour (Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R ...

unmixing in the very final stages of magmatism.

Crystal structure

The

crystal structure In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat ...

of trona was first determined by Brown et al. (1949). The structure consists of units of 3 edge-sharing sodium polyhedra (a central octahedron flanked by septahedra), cross-linked by carbonate groups and

hydrogen bond In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ...

s. Bacon and Curry (1956) refined the structure determination using two-dimensional single-crystal

neutron diffraction Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of Neutron temperature, thermal or ...

, and suggested that the hydrogen atom in the symmetric (HC₂O₆)³⁻ anion is disordered. The environment of the disordered H atom was later investigated by Choi and Mighell (1982) at 300 K with three-dimensional single-crystal neutron diffraction: they concluded that the H atom is dynamically disordered between two equivalent sites, separated from one another by 0.211(9) Å. The dynamically disordered H atom was reinvestigated at low temperature by O'Bannon et al. 2014 and they concluded that it does not order at temperatures as low as 100K.

Uses

* Trona is a common source of

soda ash Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...

, which is a significant economic commodity because of its applications in manufacturing glass, chemicals, paper, detergents, and textiles. * It is used to condition water. * It is used to remove sulfur from both flue gases and

lignite Lignite (derived from Latin ''lignum'' meaning 'wood'), often referred to as brown coal, is a soft, brown, combustible sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35% and is considered the lowest ...

coals. * It is a product of

carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. It plays a crucial role in Climate change mitigation, limiting climate change by reducing the amount of Carbon dioxide in Earth's atmosphere, carbon dioxide in the atmosphe ...

of flue gases. * It is also used as a food additive.

Mining operations

* Rio Tinto – Owens Lake *

Magadi Soda Company The Magadi Soda Company manufactures soda ash at the Kenyan town of Magadi, Kenya, Magadi, which is in southwestern Kenya. It is the largest manufacturer of soda ash in Africa. The company was founded in 1911 and mines trona from Lake Magadi, in ...

* Searles Valley Minerals Inc. * Solvay * Tata Chemicals * Genesis Alkali formerly

Tronox Tronox Limited is an American worldwide chemical company involved in the titanium products industry with approximately 6,500 employees. Following its acquisition of the mineral sands business formerly belonging to South Africa's Exxaro Resources, ...

Alkali ''formerly FMC Corporation'' * General Chemical * Ciner Wyoming ''formerly OCI Chemical Corp.'' * ANSAC * Eti Soda, Turkey * Kazan Soda Elektrik, Turkey *

Church & Dwight Church & Dwight Co., Inc. is an American consumer goods company focusing on personal care, household products, and specialty products. The company was founded in 1847 and is headquartered in Ewing, New Jersey. It is the parent company of well-kno ...

– Green River Mine * Intrepid Potash * Simplot

References