Verdelite | Gemopedia

Verdelite refers to green tourmaline that does not contain chromium. Although green is a common color of tourmaline, not all greens are valued equally. Verdelite gems come in varying shades of green; some so saturated that direct light is necessary to see the body color. From lush grass-green to electric yellow-green to olive, and even bluish green, there is a verdelite gem to fit all tastes.
Alternate
Names
Verdelith
Colors
Dark Green, Yellowish Green, Blueish Green, Light Green, Light Brown

Verdelite Classification

Common Name

Verdelite

Species

Tourmaline

Variety

Verdelite

Colors

Dark Green, Yellowish Green, Blueish Green, Light Green, Light Brown

Alternate Names

Verdelith

Gemstone Groups

Key Separations

appearance, refractive index and high birefringence; then optic figure, pleochroism and specific gravity

Comments

Misnomer: Emeraldite. Not all verdelite is elbaite tourmaline Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH). Pyroelectric: development of opposite charges at the ends of a tourmaline crystal due to change in temperature. Piezoelectric: development of opposite charges at the ends of a tourmaline crystal when placed under stress.

Verdelite Optical Properties

Transparency

Transparent - Opaque

Refractive Index

1.624-1.644

Birefringence

0.014-0.04

Optic Character

Uniaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Variable
LWUV: Variable

CCF Reaction

Pleochroism

Dichroic, strong dark green and yellow-green

Dispersion

Strength: moderate fire Value: 0.017

Comments

Verdelite Chemistry & Crystallography

Chemical Name

complex boro-silicate of Al, Mg and Fe

Chemical Formula

Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Verdelite Characteristic Physical Properties

Hardness

7-7.5

Streak

White

Specific Gravity

3-3.26 Typical:3.06

Toughness

Good

Inclusions

Verdelite tourmaline is Type I clarity stone. Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.

Luster

Vitreous

Stability

Very Good

Fracture

Conchoidal, Uneven

Cleavage

Poor, in two directions

Comments

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