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Bytownite is a rare variety of feldspar named for deposits found in Bytown, Canada (now Ottawa). Some forms of this gem distinctly resemble the gemstone andalusite, another member of the feldspar group.

Bytownite Polished
Bytownite Classification
Common Name Bytownite
Species Feldspar
Bytownite Optical Properties
Transparency Transparent - Translucent
Dispersion Strength: Weak Fire Value: 0.012
Refractive Index 1.561-1.583
Birefringence 0.007-0.011
Optic Character Biaxial
Optic Sign Negative
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism Unobservable
Bytownite Characteristic Physical Properties
Hardness 6-6.5
Streak White
Specific Gravity 2.720-2.740
Toughness Poor
Inclusions Bytownite might show labradorescence.
Luster Vitreous, Dull
Fracture Conchoidal, Uneven
Cleavage Perfect, in one direction, Good, in one direction
Bytownite Chemistry & Crystallography
Chemical Name calcium sodium aluminum silicate
Chemical Formula (Ca,Na)(Al,Si)AlSi2O8
Crystal System Triclinic
Chemistry Classification Silicate

Bytownite Colors

  • Gray Bytownite Gray
  • Yellow Bytownite Yellow
  • Brown Bytownite Brown
  • White Bytownite White

Countries of Origin


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Tim Matthews


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.