THE MINERAL GAYLUSSITE

Chemistry: Na₂Ca(CO₃)₂ - 5H₂O , Hydrated Sodium Calcium Carbonate.
Class: Carbonates
Uses: Only as mineral specimens.
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 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.

PHYSICAL CHARACTERISTICS:

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 pirssonite, northupite, trona, analcime and halite.
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.