A carbonate mineral found as white or yellowish crystals and associated chiefly with evaporite deposits formed from freshwater lakes.
Gaylussite is a double carbonate of sodium and calcium, Na₂Ca(CO₃)₂.5H₂O. Crystal system: monoclinic.
Early 19th century; earliest use found in Brande's Journal. From French gaylussite from Gay-Luss- (in the name of J.-L. Gay-Lussac) + -ite.