Fluoro-pargasite

fluoro-pargasite

titanite

actinolite

diopside

Images

Formula: NaCa(Mg4Al)(Si6Al2)O22F2
Inosilicate (chain silicate), pargasite group, amphibole supergroup
Crystal System: Monoclinic
Specific gravity: 3.18 measured, 3.19 calculated
Hardness: 6
Streak: Grey to greenish grey
Colour: Black
Luminescence: No fluorescence under UV
Environments

Metamorphic environments

Fluoro-pargasite is a relatively new mineral,approved in 2003. It occurs in granulite facies metacarbonate rocks, associated with calcite, actinolite, titanite, phlogopite and diopside (HOM).

Localities

At the type locality, Edenville, Town of Warwick, Orange county, New York, USA, fluoro-pargasite occurs in the Franklin Marble, a late Precambrian metacarbonate sequence outcropping in New Jersey and New York State. The metamorphic grade is probably upper amphibolite to granulite facies. The peak conditions of metamorphism for the Franklin Marble, in the area where the holotype material is reported to have come from, have been estimated to be 836 ± 40°C and 4 to 7 kbar. The holotype specimen consists of a 13 x 7 x 4.5 cm3 stubby black prismatic crystal associated with calcite, actinolite, and titanite, with phlogopite on its cleavage and crystal faces.
Specimens from Edenville in the Seaman Museum collection are similar, but with titanite and diopside as the only associated species (CM 43.1423-1428).

A specimen from Russell, St. Lawrence county, New York, USA, is from another sequence of Precambrian carbonates characterised by similar peak conditions of metamorphism (CM 43.1423-1428).

Back to Minerals