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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
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
