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

[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.

This article about a specific carbonate mineral is a stub.