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Schorl is the most common species of tourmaline, however, it is not as commonly faceted as its brightly colored brothers and sisters because of its black color. Well-formed schorl crystals make striking mineral specimens and long, thin schorl crystals are frequently found in quartz, called "tourmalinated quartz."

Schorl Polished
Schorl Classification
Common Name Schorl
Species Tourmaline
Schorl Optical Properties
Transparency Opaque-Semitranslucent
Dispersion Strength: None
Refractive Index 1.635-1.672
Birefringence 0.027- 0.032
Optic Character Uniaxial
Optic Sign Negative
Polariscope Reaction Doubly Refractive (DR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism Unobservable
Schorl Characteristic Physical Properties
Hardness 7-7.5
Streak White
Specific Gravity 3.000-3.260 Range:0.2/-0.06 Typical:3.060
Toughness Good
Inclusions Schorl often has tube-like 2-phase inclusions running parallel to crystal's principle axis, film-like, irregular or thread-like liquid inclusions, angular thin film mirror-like inclusions, gas inclusions in mesh-like pattern, parallel oriented hollow tubes or needles.
Luster Vitreous, Resinous
Stability Very Good
Fracture Conchoidal, Uneven
Cleavage Poor, in two directions
Schorl Chemistry & Crystallography
Chemical Name Sodium Iron Aluminum Boro-Silicate Hydroxide
Chemical Formula Na(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Crystal System Trigonal
Chemistry Classification Silicate

Schorl Colors

  • Green Schorl Green
  • Black Schorl Black
  • Brown Schorl Brown

Alternate Names

black tourmaline

Countries of Origin

Pakistan; Namibia; Madagascar

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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.