Actinolite

saf-ahyuh r

Generally transparent or translucent green, green-black, or grey-green in color, actinolite is named after the Greek word for "ray" or "beam," aktinos, referring to its fibrous nature. Actinolite also goes by the nickname 'ray stone' and is fairly prevalent worldwide.

Actinolite Polished
Actinolite Classification
Common Name Actinolite
Species Amphibole
Actinolite Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: None
Refractive Index 1.614-1.641
Tolerance:(+0.014/-0.014)
Birefringence 0.022-0.027
Optic Character Biaxial
Optic Sign Negative
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism Dichroic, moderate yellow and dark green.
Actinolite Characteristic Physical Properties
Hardness 5-6
Streak White
Specific Gravity 2.950-3.100 Typical:3.000
Toughness Varies
Inclusions It is the fibrous structure that causes chatoyancy.
Luster Vitreous
Stability Good
Fracture Even
Cleavage Perfect, in two directions
Actinolite Chemistry & Crystallography
Chemical Name calcium magnesium iron silicate hydroxide
Chemical Formula Ca2(Mg, Fe)5Si8O22(OH)2
Crystal System Monoclinic
Chemistry Classification Silicate

Actinolite Colors

  • Black Actinolite Black
  • Green Actinolite Green
  • Brown Actinolite Brown
  • White Actinolite White
  • Gray Actinolite Gray

Alternate Names

Smaragdite

Countries of Origin

Canada; Sri Lanka; Brazil

History

Strangely needle-like in nature, actinolite is often found as inclusions within other stones. If you've ever seen quartz with radiating inner "needles", you've probably seen actinolite. Popular with collectors, this generally transparent to translucent stone is often seen in needle-like form. Byssolite, a fibrous variety of actinolite, is one of two minerals responsible for the horsetail effect that makes demantoid garnet so desirable. Actinolite gets its name from the Greek word "atkinos" which means ray or beam. It's also sometimes called ray stone. Actinolite is generally transparent or translucent green, green-black, or gray-green in color. When actinolite exhibits as phenomena, it's called cat's-eye and is stunning. Actinolite is a 5.5 - 6 on the Mohs scale of hardness. It cleaves easily and is hard to cut.

Care

Exercise care when cleaning your actinolite. A soft cloth should keep it looking its best.

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More About Actinolite

Although actinolite is prevalent worldwide, there isn't much folklore that surrounds it. Those who believe in the metaphysical believe that actinolite balances body, mind, and spirit.

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Optical Phenomena

Cat's Eye

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.

Cat's Eye Actinolite
Cat's Eye Classification
Common Name Cat's Eye
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.