Meionite

minerals

scapolite

titanite

zircon

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Formula:Ca4Al6Si6O24(CO3)
Tectosilicate (framework silicate), scapolite group. Scapolite is the marialite-meionite series
Specific gravity: 2.74 to 2.78
Hardness: 5 to 6
Streak: White
Colour: Colourless, white, grey, pink, violet, blue, yellow, orange-brown, brown
Solubility:
Common impurities: Mg,Na,K,Cl,H2O,S
Environments:

Igneous environments
Pegmatites
Metamorphic environments typical

Meionite occurs typically in regionally metamorphosed rocks, especially marble, calcareous gneiss, granulite and greenschist. Also in skarn, some pegmatites, altered mafic igneous rocks and ejected volcanic blocks. Associated minerals include plagioclase, garnet, pyroxene, amphibole, apatite, titanite and zircon (HOM).

Localities

At the type locality, Monte Somma, Somma-Vesuvius Complex, Naples, Campania, Italy, meionite was found in a geode from volcanic ejecta mainly composed of limestone associated with pyroxene and leucite (AM 67.1229-1241).

At Manchester, New Hampshire, USA, meionite has been found as irregular columnar masses in a biotite schist with narrow calcareous bands interbedded with granite and pegmatite lenses (AM 67.1229-1241).

Approximately 100 meters northeast of the wollastonite - diopside locality off Rose Road, Pitcairn, Saint Lawrence county, New York, USA, there is another collecting site where meionite occurs as sharp prismatic crystals to 20 cm, and massive, yellow-gray meionite that fluoresces bright yellow in longwave ultraviolet radiation occurs in pegmatitic intergrowths with diopside and calcite (R&M 90.5.446).

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