Hawk's-Eye Quartz | Gemopedia

Hawks eye quartz is grayish blue in color due to the presence of crocidolite fibers which are intergrown with quartz producing a wavy, chatoyant shimmer. The word chatoyant comes from the French word chatoyer, meaning to shine like a cat's eyes. When the fibers of crocidolite oxidize (a form of alteration due to contact with air), they turn golden brown, producing the related quartz variety, tigers eye.
Alternate
Names
Hawk's-Eye, Falcon's-Eye
Colors
Gray To Grayish Blue, Blue Green

Hawk's-Eye Quartz Classification

Common Name

Hawk's-Eye Quartz

Species

Quartz

Variety

Hawk's-Eye Quartz

Colors

Gray To Grayish Blue, Blue Green

Alternate Names

Hawk's-Eye, Falcon's-Eye

Gemstone Groups

Key Separations

Appearance, RI and SG. Magnification and fluorescence might be helpful.

Comments

Hawk's-eye quartz is a form of tiger's eye where the quartz has replaced by the mineral crocidolite.

Hawk'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

Hawk's-Eye Quartz Chemistry & Crystallography

Chemical Name

silicon dioxide (aka silica)

Chemical Formula

SiO2

Synthesis

Crystal System

Trigonal

Classification

Silicate

Nature

Natural

Crystallinity

Aggregate

Comments

Hawk's-Eye Quartz Characteristic Physical Properties

Hardness

7

Streak

Specific Gravity

2.64-2.69 Typical:2.66

Toughness

Good

Inclusions

The cat's-eye of the stone will be the same color as the body of the stone and will be easy to see. Hawk's-eye quartz has a wavy, parallel, fibrous structure and the cat's-eye will have a wavy appearance.

Luster

Vitreous

Stability

Good

Fracture

Splintery

Cleavage

None

Comments

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