Elbaite (Tourmaline) | Gemopedia

The tourmaline family consists of at least 14 distinct minerals, but the variety elbaite accounts for nearly all gem-quality tourmaline. It was named as a result of the colored and colorless tourmalines found on the picturesque island of Elba off the western coast of Italy--history buffs know this island as the place where Napoleon Bonaparte was exiled in 1814. Although best known in shades of green and red, elbaite can also be blue, purple, yellow, or colorless. Notable varieties of elbaite include rubellite, green tourmaline, indicolite, watermelon tourmaline, Paraiba tourmaline and colorless.
Colors
Green, Blue, Red, Orange, Yellow, Colorless

Elbaite (Tourmaline) Classification

Common Name

Elbaite (Tourmaline)

Species

Elbaite

Variety

Colors

Green, Blue, Red, Orange, Yellow, Colorless

Alternate Names

Gemstone Groups

Key Separations

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

Comments

Dark material might have birefringence as high as 0.040Paraba Tourmaline is a Cuprian Elbaite.Rubellite is the red to pink variety.

Elbaite (Tourmaline) Optical Properties

Transparency

Transparent - Translucent

Refractive Index

1.614-1.666

Birefringence

0.014-0.032

Optic Character

Uniaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Dichroic, moderate to strong, varying shades of body color

Dispersion

Strength: moderate fire Value: 0.017

Comments

Elbaite (Tourmaline) 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

Elbaite (Tourmaline) Characteristic Physical Properties

Hardness

7-7.5

Streak

White

Specific Gravity

2.9-3.1

Toughness

Good

Inclusions

Green elbaite tourmaline stones are type I clarity stones. Blue, purple, orange, yellow and bi-color or parti-colored elbaite tourmalines are type II clarity stones. 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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