Thermonatrite

Thermonatrite is a naturally occurring evaporite mineral form of sodium carbonate, Na₂CO₃·H₂O.

It was first described in 1845. Its name is from the Greek θερμός, "thermos", heat, plus natron, because it may be a dehydration product of natron.

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.