Trona (trisodium hydrogendicarbonate hydrate, also sodium sesquicarbonate dihydrate, Na2CO3·NaHCO3·2H2O) is a non-marine evaporite mineral.[ Mineral galleries , 2008] It is Mining as the primary source of sodium carbonate in the United States, where it has replaced the Solvay process 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 (trona) or Spanish (trona), with both possible sources having the same meaning as in English: the mineral
natron from North Africa. Both the Spanish and Swedish
terms derive from the Arabic
trōn, which in turn derives from Arabic
natron and Hebrew rtl=yes (
natruna), which comes from
ancient Greek νιτρον (
nitron), derived ultimately from
ancient Egyptian ntry (or
nitry).
Natural deposits
near the town of Trona, California]] Trona is found at
Owens Lake and
Searles Lake,
California; the Green River Formation of
Wyoming and
Utah; the Makgadikgadi Pans in
Botswana and in the
Nile Valley in
Egypt.
[C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham] The trona near Green River, Wyoming, is the largest known deposit in the world and lies in layered
evaporite deposits below ground, where the trona was deposited in a lake during the
Paleogene 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 is covered by a 1.5 m thick trona bed,
[Manega, P.C., Bieda, S., 1987. Modern sediments of Lake Natron, Tanzania. Sciences Geologiques. Bulletin 40, 83–95.] and occurs in 'salt' pans in the Etosha National Park in
Namibia.
[Eckardt, F. D., Drake, N., Goudie, A. S., White, K., & Viles, H. (2001). The role of playas in pedogenic gypsum crust formation in the Central Namib Desert: a theoretical model. Earth Surface Processes and Landforms, 26(11), 1177–1193.] The
Beypazari region in the
Ankara Province of
Turkey has some 33 trona beds in two fault-bound lensoid bodies in and above
of the Lower Hirka Formation (16 in the lower and 17 in the upper body).
[Helvaci, C., 1998. The Beypazari trona deposit, Ankara Province, Turkey. In: Dyni, J.R., Jones, R. W. (Eds.), Proceedings of the first international soda-ash conference; Volume II, v. 40: Laramie, WY, Public Information Circular – Geological Survey of Wyoming, pp. 67–103.] The Wucheng basin trona mine,
Henan Province China 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.
[Zhang, Youxun, 1985. Geology of the Wucheng trona deposit in Henan, China. In: Schreiber, B.C., Warner, H.L. (Eds.), Sixth international symposium on salt, 1, pp. 67–73.]
Trona has also been found in magmatic environments.
Crystal structure
The crystal structure 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
. Bacon and Curry (1956)
[Bacon, G.E., and Curry, N.A. (1956) A neutron-diffraction study of sodium sesquicarbonate. Acta Crystallographica, 9, 82–85.] refined the structure determination using two-dimensional single-crystal neutron diffraction, and suggested that the hydrogen atom in the symmetric (HC
2O
6)
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
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Trona is a common source of soda ash, which is a significant economic commodity because of its applications in manufacturing glass, chemicals, paper, detergents, and textiles.
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It is used to condition water.
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It is used to remove sulfur from both and lignite coals.
[Kong Y., and Wood M.D. (2010) Dry injection of trona for SO3 control. Power, 154, 114–118.]
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It is a product of carbon sequestration of .
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It is also used as a food additive.
Mining operations
See also
