Pargasite | Gemopedia

Pargasite mostly occurs in a brown color, but has been found in greenish-brown to dark green and black. This gemstone was first found in Finland in 1814 and is named for its site of discovery. A member of the amphibole group, pargasite is closely related to hornblende. Some fine specimens of this rare gemstone have been faceted.
Alternate
Names
Pargasitic Hornblende
Colors
Bluish Green, Emerald Green, Greenish Brown Brown, Light Brown, Black

Pargasite Classification

Common Name

Pargasite

Species

Pargasite

Variety

Colors

Bluish Green, Emerald Green, Greenish Brown Brown, Light Brown, Black

Alternate Names

Pargasitic Hornblende

Gemstone Groups

Amphibole

Key Separations

RI, birefringence

Comments

Pargasite Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.613-1.663

Birefringence

0.02-0.024

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Trichroic, (in brown gems) moderate to strong colorless, yellow, and brown; (in green gems) moderate to strong greenish yellow, green, and greenish blue

Dispersion

Strength: weak fire

Comments

Pargasite Chemistry & Crystallography

Chemical Name

Chemical Formula

NaCa2(Mg4Al)Si6Al2O22(OH)2

Synthesis

Crystal System

Monoclinic

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline to Aggregate

Comments

Pargasite Characteristic Physical Properties

Hardness

5-6

Streak

Specific Gravity

3.04-3.26

Toughness

Poor

Inclusions

Luster

Vitreous

Stability

Fracture

Uneven

Cleavage

Perfect, in one direction

Comments

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