Thermonatrite

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Thermonatrite
Villiaumite5 - Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada.jpg
Villiaumite and thermonatrite (powdery coating)
General
CategoryCarbonate mineral
Formula
(repeating unit)
Na2CO3·H2O
Strunz classification5.CB.05
Crystal systemOrthorhombic
Crystal classPyramidal (mm2)
H-M symbol: (mm2)
Space groupPca21
Unit cella = 10.72 Å, b = 5.24 Å
c = 6.46 Å; Z = 4
Identification
ColourColourless to grey or yellow, white
Crystal habitAcicular crystals rare; typically occurs as powdery crusts
CleavagePoor to indistinct on {100}
FractureSectile
Mohs scale hardness1 - ​1 12
LustreVitreous
DiaphaneityTransparent
Specific gravity2.255 (measured on synthetic crystal)
Optical propertiesBiaxial (-)
Refractive indexnα = 1.420 nβ = 1.506 nγ = 1.524
Birefringenceδ = 0.104
2V angle48° (measured)
SolubilitySoluble in water
Other characteristicsReadily 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]

References[edit]