Indicolite | Gemopedia

Indicolite is one of the most valuable and collectible of all elbaite tourmalines, with hues spanning from lighter to deep, intense blues. Cutting indicolite can be a task for even the most skilled of cutters, as it is strongly pleochroic and appears darker when viewed down the crystal. This factor must be taken into consideration when cutting, as a loss of transparency and brilliance can occur in darker specimens.
Alternate
Names
Indigolite, Aqualite
Colors
Violet To Greenish Blue

Indicolite Classification

Common Name

Indicolite

Species

Elbaite

Variety

Indicolite

Colors

Violet To Greenish Blue

Alternate Names

Indigolite, Aqualite

Gemstone Groups

Tourmaline

Key Separations

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

Comments

Crystal habit is prismatic and may be 3, 6 or 9-sided; often a triangular prism with convex faces, and often long and heavily striated parallel to the c axis. Pyramidal terminations are common. Tourmaline is part of an isomorphous series.Dark material might have a birefringence as high as 0.040

Indicolite Optical Properties

Transparency

Transparent - Opaque

Refractive Index

1.624-1.644
Tolerance:-1.22222222222222

Birefringence

0.018-0.02

Optic Character

Uniaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert to weak bluish green
LWUV: Inert to weak bluish green

CCF Reaction

Pleochroism

Dichroic, strong dark blue and light blue

Dispersion

Strength: moderate fire Value: 0.017

Comments

Indicolite 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

Indicolite Characteristic Physical Properties

Hardness

7-7.5

Streak

White

Specific Gravity

3-3.26 Range:0.2/-0.06 Typical:3.06

Toughness

Good

Inclusions

Indicolite is a type II 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

Cleavage

Poor, in two directions

Comments

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