Tiger's-Eye Quartz | Gemopedia

Tiger's eye is a unique and mysterious member of the quartz family. It ranges in color from rich, golden yellow to bronze and brown. Best seen when gems are cut en cabochon, tiger's eye displays an optical phenomenon known as chatoyancy. Unlike other chatoyant gems, tigers eye quartz is made up of quartz with intergrown fibers of amphibole that were altered to golden or rusty-brown limonite. When light hits the surface of this gem, a silky, wavy shimmer moves across the surface of the stone resembling the eye of a tiger. A related variety of quartz, called hawks eye, is blue due to unaltered inclusions of crocidolite.
Alternate
Names
Hawk-Eye, Falcon's-Eye, Zebra Tiger's-Eye, Cat's-Eye
Colors
Brownish Yellow To Brownish Reddish Brown Unless Dyed Then Stones Can Be Any Color

Tiger's-Eye Quartz Classification

Common Name

Tiger's-Eye Quartz

Species

Quartz

Variety

Tiger's-Eye

Colors

Brownish Yellow To Brownish Reddish Brown Unless Dyed Then Stones Can Be Any Color

Alternate Names

Hawk-Eye, Falcon's-Eye, Zebra Tiger's-Eye, Cat's-Eye

Gemstone Groups

Key Separations

Color, appearance, structure and RI

Comments

Misnomer: crocidolite. Tiger's-eye is formed by parallel intergrowth of quartz crystals and altered amphibole fibers that mostly turned into limonite.

Tiger's-Eye Quartz Optical Properties

Transparency

Semitranslucent - Opaque

Refractive Index

1.544-1.553
Tolerance:very constant

Birefringence

0.009

Optic Character

Uniaxial

Optic Sign

Positive

Polariscope Reaction

Aggregate (AGG)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

None

Dispersion

Comments

Tiger's-Eye Quartz Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Macrocrystalline

Comments

Tiger's-Eye Quartz Characteristic Physical Properties

Hardness

7

Streak

Yellow-Brown

Specific Gravity

2.64-2.69 Typical:2.66

Toughness

Good

Inclusions

Tiger's-eye has a wavy fibrous structure. If the stone is dyed there will be dye concentrations along the fibers.

Luster

Vitreous

Stability

Good

Fracture

Splintery

Cleavage

None

Comments

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