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Formula: Na2Ca(CO3)2.5H2O
Hydrated normal carbonate
Crystal System: Monoclinic
Specific gravity: 1.991 measured and calculated
Hardness: 2½
Streak: White
Colour: Colourless, white
Luminescence: Fluoresces blue-white under long wave UV
Solubility: Soluble with effervescence in acids. Dehydrates with efflorescence in dry air, slowly decomposes in water leaving
CaCO3 as calcite or aragonite.
Environments
Gaylussite is usually found in soda lakes with natron,
thermonatrite, trona,
pirssonite, calcite,
borax and rarely tychite
(Dana).
Localities
At the Khibiny Massif, Murmansk Oblast, Russia, gaylussite is associated with
thermonatrite, shortite,
villiaumite, Fe3+-rich biotite,
pectolite, K-feldspar and
aegirine
(HOM).
At Borax Lake, Clear Lake Oaks, Sulphur Creek Mining District, Lake county, California, USA, gaylussite is found
with northupite and pirssonite
(Dana).
At the Green River Basin, Sweetwater County, Wyoming, USA, gaylussite is associated with
shortite, northupite,
pirssonite and trona
(HOM).
Alteration
Gaylussite dehydrates with efflorescence in dry air. It alters readily to
calcite.
Calcite pseudomorphs after gaylussite
have been described.
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