- Chemistry: Na2Ca(CO3)2 - 5H2O ,
Hydrated Sodium Calcium Carbonate.
- Class: Carbonates
- Uses: Only as mineral specimens.
Gaylussite is named for French chemist and physicist J. L. Gay-lussac.
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
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.
Transparency: Crystals are transparent to translucent.
Crystal System is monoclinic; 2/m.
Crystal Habits include intricately faceted prismatic to tabular crystals, but also massive and encrusting.
Cleavage is perfect in two directions.
Fracture is conchoidal.
Hardness is 2 - 3.
Specific Gravity is 1.9 - 2.0 (well below average)
Streak is white.
Associated Minerals include
Notable Occurrences include Searles Lake, San Berardino County;
Deep Spring and Owens Lake, Inyo County; Borax Lake, Lake County and China Lake, Kern County, California, USA;
Gobi Desert, Mongolia and Lagunillas, Merida, Venezuela.
Best Field Indicators: Crystal habit, environment of formation, cleavage, density and locality.