Thermonatrite
| Thermonatrite | |
|---|---|
|
Villiaumite and thermonatrite (powdery coating) | |
| General | |
| Category | Carbonate mineral |
| Formula (repeating unit) | Na2CO3·H2O |
| Strunz classification | 05.CB.05 |
| Crystal symmetry |
Orthorhombic pyramidal H-M symbol: (mm2) Space group: P ca21 |
| Unit cell | a = 10.72 Å, b = 5.24 Å, c = 6.46 Å; Z=4 |
| Identification | |
| Colour | Colourless to grey or yellow, white |
| Crystal habit | Acicular crystals rare; typically occurs as powdery crusts |
| Crystal system | Orthorhombic |
| Cleavage | Poor to indistinct on {100} |
| Fracture | Sectile |
| Mohs scale hardness | 1 - 1½ |
| Luster | Vitreous |
| Diaphaneity | Transparent |
| Specific gravity | 2.255 (measured on synthetic crystal) |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.420 nβ = 1.506 nγ = 1.524 |
| Birefringence | δ = 0.104 |
| 2V angle | 48° (measured) |
| Solubility | Soluble in water |
| Other characteristics | Readily dehydrates |
| References | [1][2][3] |
Thermonatrite is a naturally occurring evaporite mineral form of sodium carbonate, Na2CO3·H2O.[1][2]
It was first described in 1845.[3] Its name is from the Greek θερμός, "thermos", heat, plus natron, because it may be a dehydration product of natron.[2]
Typical occurrence is in dry saline lake beds and as soil encrustations. It has been reported from volcanic fumaroles and in association with carbonatite related veins. Common associated minerals include trona, natron and halite.[1]