| Thermonatrite | |
| Category: | Carbonate mineral |
| Formula: | Na2CO3·H2O |
| Imasymbol: | Tnat[1] |
| Strunz: | 5.CB.05 |
| System: | Orthorhombic |
| Class: | Pyramidal (mm2) H-M symbol: (mm2) |
| Symmetry: | Pca21 |
| Unit Cell: | a = 10.72 Å, b = 5.24 Å c = 6.46 Å; Z = 4 |
| Colour: | Colourless to grey or yellow, white |
| Habit: | Acicular crystals rare; typically occurs as powdery crusts |
| Cleavage: | Poor to indistinct on |
| Fracture: | Sectile |
| Mohs: | 1 – |
| Lustre: | Vitreous |
| Diaphaneity: | Transparent |
| Gravity: | 2.255 (measured on synthetic crystal) |
| Opticalprop: | Biaxial (−) |
| Refractive: | nα = 1.420 nβ = 1.506 nγ = 1.524 |
| Birefringence: | δ = 0.104 |
| 2V: | 48° (measured) |
| Solubility: | Soluble in water |
| Other: | Readily dehydrates |
Thermonatrite is a naturally occurring evaporite mineral form of sodium carbonate, Na2CO3·H2O.[2] [3]
It was first described in 1845.[4] Its name is from the Greek θερμός thermos, "heat", plus natron, because it may be a dehydration product of natron.[3]
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.[2]