Trona

Trona
General
Category	Carbonate mineral
Formula (repeating unit)	Na2CO3·NaHCO3·2H2O
IMA symbol	Tn[1]
Strunz classification	5.CB.15
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/c (no. 15)
Identification
Color	Colorless (in transmitted light) or white, grey-white, also grey to yellowish grey, light yellow
Crystal habit	Columnar, fibrous and massive.
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	[2][3][4][5]

Trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, Na₂CO₃·NaHCO₃·2H₂O) is a non-marine evaporite mineral.^[4][6] 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. Turkey is also a major producer.