Tro"na (?), n. [Of Egyptian or North African origin.] Chem. & Min.
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.
© Webster 1913.