Gaylussite

Infobox mineral
name = Gaylussite
category = Carbonate mineral
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formula = Na₂Ca(CO₃)₂·5H₂O
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color = Colorless, white, yellow, and grey
habit = Tabular prismatic crystals also granular
system = Monoclinic 2/m
twinning =
cleavage = perfect [110]
fracture = Conchoidal, brittle
mohs = 2.5
luster = vitreous
refractive = nα = 1.444 nβ = 1.516 nγ = 1.523
opticalprop = Biaxial (-)
birefringence = δ = 0.079
pleochroism =
streak = white
gravity = 1.93 - 1.99
density =
melt =
fusibility =
diagnostic =
solubility = decomposes in water
diaphaneity =
other = efflorescent
references = http://rruff.geo.arizona.edu/doclib/hom/gaylussite.pdf Handbook of Mineralogy] http://www.mindat.org/min-1662.html Mindat] http://webmineral.com/data/Gaylussite.shtml Webmineral]

Gaylussite is a carbonate mineral, a hydrated sodium calcium carbonate, formula Na₂Ca(CO₃)₂·5H₂O. It occurs as translucent, vitreous white to grey to yellow monoclinic prismatic crystals. It is an unstable mineral which dehydrates in dry air and decomposes in water.

It is formed as an evaporite from alkali lacustrine waters. It also occurs rarely as veinlets in alkalic igneous rocks.

It was first described in 1826 for an occurrence in Lagunilla, Mérida, Venezuela. It was named for French chemist Joseph Louis Gay-Lussac (1778-1850).

References