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Trona sample
Category Carbonate mineral
(repeating unit)
Strunz classification 05.CB.15
Color Colorless or white, also grey to yellowish grey
Crystal habit Columnar, fibrous and massive.
Crystal system Monoclinic - Prismatic 2/m
Cleavage [100] perfect, [111] and [001] indistinct
Fracture Brittle - subconchoidal
Mohs scale hardness 2.5
Luster Vitreous
Streak White
Diaphaneity Translucent
Specific gravity 2.11 - 2.17
Optical properties Biaxial (-)
Refractive index nα = 1.412 nβ = 1.492 nγ = 1.540
Birefringence δ = 0.128
Solubility Soluble in water
Other characteristics May fluoresce under short wavelength ultraviolet
References [1][2][3]

Trona (trisodium hydrogendicarbonate dihydrate); Na3(CO3)(HCO3)•2H2O is an evaporite mineral.[3][4] It is mined 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.


The word "trona" comes to English by way of either Swedish (trona) or Spanish (trona), with both possible sources having the same meaning as in English. Both of these derive from the Arabic trōn which in turn derives from the Arabic natron, and Hebrew נטרן (natruna), which comes from ancient Greek νιτρον (nitron), derived ultimately from ancient Egyptian ntry (or nitry).

Natural deposits[edit]

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.[5] The trona near Green River, Wyoming is the largest known deposit in the world and lies in layered evaporite deposits from 800 to 1,600 feet (240 to 490 m) below ground, where the trona was deposited in a lake during the Paleogene period.[6] Trona has also been mined at Lake Magadi in the Kenyan Rift Valley for nearly 100 years, and occurs in 'salt' pans in the Etosha National Park in Namibia.[citation needed]

Mining operations[edit]

See also[edit]


  1. ^ Handbook of Mineralogy
  2. ^ Mindat
  3. ^ a b Webmineral data
  4. ^ Mineral galleries, 2008
  5. ^ C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham
  6. ^ Banks, Chad (2007-05-24). What is Trona? Wyoming Mining Association. Retrieved on 2009-07-01.