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Formula: Na4Al3Si9O24Cl
Tectosilicate (framework silicate), scapolite group, forms a series with
meionite
Specific gravity: 2.5 to 2.62
Hardness: 5½ to 6
Streak: White
Colour: Colourless, white, bluish, brownish, yellowish, violet, greenish
Solubility:
Common impurities: Fe,Ca,K,S
Environments
Volcanic igneous environments
Pegmatites
Metamorphic environments
Hydrothermal environments
Marialite typically occurs in regionally metamorphosed rocks, especially
marble, calcareous gneiss,
granulite and greenschist. It also
occurs in skarn, some pegmatites,
pneumatolytically or hydrothermally altered mafic igneous rocks and ejected volcanic blocks.
Associated minerals include plagioclase, garnet,
pyroxenes, amphiboles,
apatite, titanite and
zircon
(HOM, Mindat).
Localities
At the Rose Road locality, Pitcairn, St. Lawrence county, New York, USA, marialite occurs as white outer zones on grey
meionite crystals
(R&M 90.5.446).
At the Selleck Road Tremolite and Tourmaline Locality,
West Pierrepont, St. Lawrence County, New York, USA, marialite occurs as prismatic crystals to 10 cm in complex clusters to 20 cm.
Most crystals are altered to creamy white microcline, at least on their surfaces, and many have
been completely replaced by that mineral. Unaltered marialite is most common in the Walter-Crump pit, the Walter-Wallace pit, and the
Carlin trench.
At the Walter-Crump pit, tremolite crystals, large diopside
crystals, some altered to, and overgrown by, tremolite, and
quartz crystals formed along the contacts a series of convoluted contacts between
marble and
tremolite-diopside rock. Locally masses of
lavender marialite were encountered in groups of interlocking crystals, mostly altered to
microcline except in the centres.
At the Walter-Wallace pit significant specimens of lavender marialite crystals, often partially replaced by creamy white
microcline, were recovered from a large pocket of
fluor-uvite crystals.
At the Carlin trench marialite was found in a vein that also contained phlogopite triplet
twins, albite, microcline,
heulandite-Ca, and fluor-uvite
(R&M 91-2.123).
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