trona

A natural vitreous gray or white mineral, Na₂CO₃·NaHCO₃·2H₂O, used as a source of sodium compounds.

The native soda of Egypt, a hydrous carbonate of sodium, Na₂CO₃.HNaCO₃ + 2H₂O.

A native double salt, consisting of a combination of neutral and acid sodium carbonate, Na2CO3.2HNaCO3.2H2O, occurring as a white crystalline fibrous deposit from certain soda brine springs and lakes; — called also urao, and by the ancients nitrum.

A saline evaporite, consisting of mixture of sodium carbonate and sodium bicarbonate, Na3HCO3CO3·2H2O.