thermonatrite

thermonatrite, a carbonate mineral, hydrated sodium carbonate (Na₂CO₃·H₂O), found near saline lakes as an evaporation product or on arid soil as an efflorescence. It is usually associated with natron (Na₂CO₃·10H₂O) and trona, which alter to it upon partial dehydration; many reported deposits of natron are probably thermonatrite, because normal temperatures and dry air will cause the alteration. Natron, commonly found in solution, was used by ancient Egyptians as a preservative in mummification. For detailed physical properties, see carbonate mineral (table).