Hauyne

Infobox mineral
name = Hauyne
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formula = (Na,Ca)_4-8Al₆Si₆(O,S)₂₄(SO₄,Cl)_1-2
color = Blue, white, grey, ...
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system = Isometric
twinning =
cleavage = Distinct/Good, Distinct on {110}
fracture = Irregular/Uneven, Conchoidal
mohs = 5 to 6
luster = Vitreous, Greasy
refractive = n = 1.494 - 1.509
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gravity = 2.4 to 2.5
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Hauyne, haüyne or hauynite is a tectosilicate mineral with sulfate and chloride with formula: (Na,Ca)_4-8Al₆Si₆(O,S)₂₄(SO₄,Cl)_1-2. It is a feldspathoid and a member of the sodalite group. Hauyne crystallizes in the isometric system forming translucent, vitreous typically twinned crystals with highly variable color (blue, white, grey, yellow, green, pink). It has a Mohs hardness of 5 to 6 and a specific gravity of 2.4 to 2.5.

Hauyne was first described in 1807 from samples at Vesuvius Mount Somma, Italy. It was named for the French crystallographer, Rene Just Hauy (1743-1822). It occurs in silica deficient igneous rocks in a wide variety of locations.

References

* [http://www.mindat.org/min-1833.html Mindat with location list]
* [http://webmineral.com/data/Hauyne.shtml Webmineral]