Praseolite | Gemopedia

Some times called Green Amethyst, Prasiolite is a green variety of quartz that is easily be mistaken for other gemstones like peridot. Despite prasiolites affordability, it is definitely unusual and remains a collectors gemstone. In order to get this leaf-green color that is prasiolite the gemstone must be heated, but this process only results in about 30% of the lot will in true green color.
Alternate
Names
Green Quartz, \"Greened Amethyst\"

Praseolite Classification

Common Name

Praseolite

Species

Quartz

Variety

Praseolite

Colors

green to yellowish green

Alternate Names

green quartz, "greened amethyst"

Gemstone Groups

Key Separations

Refractive index, birefringence, optic character and optic figure. A bull's-eye optic figure is determinative for quartz. The presence of Brazil-law twinning is a means of separating amethyst from scapolite.

Comments

Misnomer: green amethyst. Green color is rarely found naturally and most are irradiated and/or heat treated.

Praseolite Optical Properties

Transparency

Transparent To Translucent

Refractive Index

1.544-1.553 Tolerance: very constant

Birefringence

0.009

Optic Character

uniaxial

Optic Sign

positive

Polariscope Reaction

doubly refractive (DR)

Fluorescence

SWUV: Generally Inert
LWUV: Generally Inert

CCF Reaction

Pleochroism

Value: weak variations of bodycolor

Dispersion

Strength: weak fire Value: 0.013

Praseolite Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Praseolite Characteristic Physical Properties

Hardness

7

Streak

white

Specific Gravity

2.64-2.69 Typical: 2.66

Toughness

Good

Inclusions

Praseolite is a type II clarity stone. Stones may contain crystals, negative crystals, liquid inclusions, two-phase inclusions and partially-healed fractures.

Luster

Vitreous

Stability

Good

Fracture

Conchoidal

Cleavage

None To Very Poor

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