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Datolite is a phyllo-borosilicate commonly forming as nodules in igneous rocks. Facet-grade material rarely yields gems larger than 10 carats, with most being significantly smaller. Colorless, transparent datolite gems can be found in several locations worldwide, but many come from Connecticut, Massachusetts, New Jersey, and Virginia. Copper-stained, opaque nodules from Michigan are typically fashioned into cabochons.

Datolite Rough
Datolite Classification
Common Name Datolite
Species Datolite
Datolite Optical Properties
Transparency Transparent - Translucent
Dispersion Strength: Weak Fire Value: 0.016
Refractive Index 1.626-1.670
Birefringence 0.044-0.046
Optic Character Biaxial
Optic Sign Negative
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Pleochroism Unobservable
Datolite Characteristic Physical Properties
Hardness 5-5.5
Specific Gravity 2.900-3.000 Typical:2.950
Toughness Fair
Luster Vitreous
Fracture Conchoidal, Uneven
Cleavage None
Datolite Chemistry & Crystallography
Chemical Name Calcium Boron Silicate Hydroxide
Chemical Formula CaBSiO4(OH)
Crystal System Monoclinic
Chemistry Classification Silicate

Datolite Colors

  • Yellow Datolite Yellow
  • Gray Datolite Gray
  • Colorless Datolite Colorless
  • White Datolite White
  • Pink Datolite Pink
  • Red Datolite Red
  • Green Datolite Green

Countries of Origin

United States of America (the)

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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.