It is sometimes a well crystallized mineral displaying good, intricately faceted monoclinic forms. Gaylussite is one of several carbonate minerals that form in non-marine evaporite deposits. Other such carbonates include trona , pirssonite , northupite , nahcolite and thermonatrite . They are all difficult to tell apart from each other except when good crystal form is present or when optical or X-ray techniques can be used. Gaylussite is subject to dehydration which can cause cloudiness and deterioration and should therefore be stored in a sealed container.
Color is colorless, white or yellowish.
Luster is vitreous. Crystals are transparent to translucent. Crystal Habits include intricately faceted prismatic to tabular crystals, but also massive and encrusting. Cleavage is perfect in two directions. Fracture is conchoidal.