Tiger's-Eye | Gemopedia

Tiger's eye is a unique and mysterious member of the quartz family. Its color is usually rich yellow to medium to dark brown. Best seen when gems are cut en cabochon, tiger's eye displays an optical phenomenon known as chatoyancy. Manifesting as a silky, wavy shimmer across the surface of the stone, this phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throught the crystal, scattering and reflecting light back to the viewer as a thin line. Tiger's eye derives its name from its color and reflective qualities that are strikingly similar to an actual tiger's eye. Red varieties of tiger's eye stones are often created using heat-treatment to enhance color. There are unusual blue varieties that are sometimes referred to as hawk's eye.
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 Classification

Common Name

Tiger's-Eye

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 Optical Properties

Transparency

Semitransluscent To Opaque

Refractive Index

1.544-1.553 Tolerance: very constant

Birefringence

0.009

Optic Character

uniaxial

Optic Sign

positive

Polariscope Reaction

aggregate (AGG) unless too opaque to test

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Dispersion

Comments

Tiger's-Eye 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 Characteristic Physical Properties

Hardness

7

Streak

yellow-brown

Specific Gravity

2.64-2.69

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 To Very Poor

Comments

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