Pargasite - Encyclopedia

    Class : Silicates
    Subclass : Inosilicates
    Crystal system : Monoclinic
    Chemistry : NaCa2Mg4Al(Si6Al2)O22(OH)2
    Rarity : Rare


Pargasite is a sodium, calcium and magnesium amphibole, once considered a variety of green hornblende. It is now recognized as a mineral in its own right and forms a continuous series with ferropargasite, its iron equivalent. It is found in metamorphic limestones and skarns, in certain gabbros and volcanic rocks as well as in weathered ultrabasic rocks. It owes its name to its place of discovery : Parainen near Pargas in Finland. Pargasite occurs in often squat prismatic crystals with pseudohexagonal sections, rarely doubly-terminated. It is also common in masses or more or less fibrous to bacillary aggregates, sometimes grainy. Its color is usually brown to brown-black, sometimes green to green-black. It is a mineral that is occasionally cut as a gemstone.

Pargasite from Aliabad, Nagar, Gilgit-Baltistan, Pakistan
Pargasite from Aliabad, Nagar, Gilgit-Baltistan, Pakistan
Pargasite from Aliabad, Nagar, Gilgit-Baltistan, Pakistan
Pargasite from Aliabad, Nagar, Gilgit-Baltistan, Pakistan

Pargasite in the World

It is an amphibole known in many localities. Very good crystals of pargasite come from its type-locality of Parainen (Finland), and metamorphic limestones of Crestmore (California), where the magnificent brown crystals reach 8 cm. The Wolf Lake marbles (Ontario, Canada) and the Kragerö gabbros (Norway) also provided very good quality crystals. The Sar-e-Sang River (Afghanistan) marbles provided 2 cm prismatic and terminated brown gemmy crystals while those of Aliabad (Pakistan) and Luc Yen (Vietnam) produced intense green gemmy crystals sometimes up to 5 cm.

Pargasite in France

In France, pargasite is reported in the surroundings of Brioude (Haute-Loire) and in the granulites of the Etang de Lers (Ariège).

Twinning

No twin known for this mineral species.

Fakes and scams

No fake recorded for this mineral species.



Hardness : 5 to 6
Density : 2.76
Fracture : 3.06 to 3.18
Streak : Brown to green




TP : Translucent to transparent
IR : 1.630 to 1.650
Biréfringence : 0.020
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : Green-white


Solubility : None

Magnetism : None
Radioactivity : None