Pargasite

pargasite

tschermakite

tremolite

albite

Images

Formula: NaCa2(Mg4Al)(Si6Al2)O22(OH)2
Inosilicate (chain silicate), amphibole group
Specific gravity: 3.069 to 3.181
Hardness: 5 to 6
Streak: White
Colour: Green, brown
Common impurities: Ti,Cr,Mn,K,F,H2O,P
Environments:

Metamorphic environments

Pargasite is a common component of skarn metamorphosed from siliceous limestone. It also may occur in schist and amphibolite.

Localities

Amity, Town of Warwick, Orange county, New York, USA, is an area of granite intrusions into marble and associated gneiss. The marble is mostly composed of white crystalline calcite that often has small flakes or spheres of graphite and phlogopite. Pargasite has been found as shiny black and dark green crystals to 5 cm in marble (R&M 96.5.438).

Alteration

magnesium-rich tremolite, tschermakite and albite to pargasite and quartz
☐Ca2Mg5Si8O22(OH)2 + ☐Ca2(Mg3Al2)(Si6Al2)O22(OH)2 + 2Na(AlSi3O8) ⇌ 2NaCa2(Mg4Al)(Si6Al2)O22(OH)2 + 8SiO2
(AM 92.4.491)

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