Trona
Trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, Na2CO3·NaHCO3·2H2O) is a non-marine evaporite mineral. 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.
| Trona | |
|---|---|
| General | |
| Category | Carbonate mineral |
| Formula (repeating unit) | Na2CO3·NaHCO3·2H2O |
| IMA symbol | Tn |
| 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 | |
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