Chrome Tourmaline

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First discovered in Tanzania in the 1960's, chrome tourmaline is a fairly new addition to the vast tourmaline family. A true collector's gem, chrome tourmaline exhibits bright green color that resembles, and even rivals, that of the finest emeralds. While it is a type of green tourmaline, not all green tourmalines contain chromium and can be called chrome tourmaline. True chrome tourmaline is more highly prized, as it is a more rare occurrence for chromium to be a coloring agent, which often results in a much brighter and richer green color.

Chrome Tourmaline Polished
Chrome Tourmaline Classification
Common Name Chrome Tourmaline
Species Tourmaline
Chrome Tourmaline Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: Moderate Fire Value: 0.017
Refractive Index 1.624-1.644
Tolerance:-( +0.011/-0.009)
Birefringence 0.018-0.02
Optic Character Uniaxial
Optic Sign Negative
Polariscope Reaction Doubly Refractive (DR)
Fluorescence SWUV: Inert to weak
LWUV: Inert to weak
CCF Reaction Reddish
Pleochroism Dichroic, strong dark green and yellow-green
Chrome Tourmaline Characteristic Physical Properties
Hardness 7-7.5
Streak White
Specific Gravity 3.000-3.260 Typical:3.060
Toughness Good
Inclusions Chrome tourmaline is a type I clarity stone. Stones might have liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.
Luster Vitreous
Stability Very Good
Fracture Conchoidal, Uneven
Cleavage Poor, in two directions
Chrome Tourmaline Chemistry & Crystallography
Chemical Name complex boro-silicate of Al, Mg and Fe
Chemical Formula Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Crystal System Trigonal
Chemistry Classification Silicate

Chrome Tourmaline Colors

  • Green Chrome Tourmaline Green

Alternate Names

Chromtourmaline, Chromium Tourmaline

Countries of Origin

Tanzania, United Republic Of; China; Nigeria

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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.