trona

Tro"na, n. Etym: [Of Egyptian or North African origin.] (Chem. & Min.) Defn: 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.

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