Actinolite (Cat's-Eye) | Gemopedia

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case actinolite. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line.
Colors
Yellowish Green, Light To Dark Green, Black

Actinolite (Cat's-Eye) Classification

Common Name

Actinolite (Cat's-Eye)

Species

Actinolite

Variety

Cat's-Eye Actinolite

Colors

Yellowish Green, Light To Dark Green, Black

Alternate Names

Gemstone Groups

Amphibole

Key Separations

Appearance, poor surface quality, RI and SG

Comments

Actinolite usually fibrous aggregate. Misnomer jade cat's-eye.

Actinolite (Cat's-Eye) Optical Properties

Transparency

Semitransparent - Opaque

Refractive Index

1.614-1.641
Tolerance:0.014

Birefringence

0.022-0.027

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Aggregate (AGG)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Dichroic, moderate yellow and dark green

Dispersion

Strength: none

Comments

Actinolite (Cat's-Eye) Chemistry & Crystallography

Chemical Name

calcium magnesium iron silicate hydroxide

Chemical Formula

Ca2(Mg, Fe)5Si8O22(OH)2

Synthesis

Crystal System

Monoclinic

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline to Aggregate

Comments

Actinolite (Cat's-Eye) Characteristic Physical Properties

Hardness

5-6

Streak

White

Specific Gravity

2.95-3.1 Typical:3

Toughness

Excellent

Inclusions

It is the fibrous structure that causes chatoyancy.

Luster

Vitreous

Stability

Good

Fracture

Uneven

Cleavage

Perfect, in two directions

Comments

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