trona

This page is about the mineral. For the town, please see Trona, California; for the geological feature, please see Trona Pinnacles.

Trona
Trona sample
General
Category	Carbonate mineral
Chemical formula	Na3(CO3)(HCO3)•2H2O
Identification
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 ultrviolet
References	[1][2][3]

Trona (trisodium hydrogendicarbonate dihydrate); Na₃H(CO₃)₂·2H₂O 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.

Natural occurrence

Trona is found at Owens Lake and Searles Lake, California; the Green River Formation of Wyoming and Utah; the Makgadikgadi Pans^[5] in Botswana and in the Nile Valley in Egypt. 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 Rift Valley in Kenya for nearly 100 years, and occurs in 'salt' pans in the Etosha National Park in Namibia.^{[citation needed]}

Etymology

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 pronounced natrun, which comes from ancient Greek νιτρον, derived ultimately from ancient Egyptian ntry (or nitry).

Companies with trona mining operations

• Magadi Soda Company
• Searles Valley Minerals Inc.
• Solvay
• Tata Chemicals
• FMC Corporation
• General Chemical
• OCI
• American Natural Soda Ash Company

See also

• Natron
• Nahcolite
• Shortite
• Sodium sesquicarbonate
• Thermonatrite

References