from The Century Dictionary.
- noun Hydrous sodium carbonate (Na2CO3 + H2O), occurring chiefly as an effiorescence in connection with saline lakes.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun mineralogy A
saline evaporite, consisting of sodium carbonate, with the chemical formula Na2 C O3·H2O.
Sorry, no etymologies found.
Sodium carbonate has three known forms of hydrates: sodium carbonate decahydrate (natron), sodium carbonate heptahydrate (not known in mineral form) and sodium carbonate monohydrate (mineral thermonatrite).