Adularia

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Adularia is a variety of feldspar found in hydrothermal veins in mountainous areas, from one of which it derives its name: the Adular Mountains of Switzerland. It commonly forms colorless to white, cream, pale yellow to pink, or reddish-brown, glassy, prismatic, twinned crystals. These transparent to colorless gems often display a white to blue sheen.

Adularia Polished
Adularia Classification
Common Name Adularia
Species Feldspar
Adularia Optical Properties
Transparency Transparent - Translucent
Dispersion Strength: Weak Fire Value: 0.12
Refractive Index 1.518-1.526
Tolerance:(+0.010/-)0.010)
Birefringence 0.005-0.008
Optic Character Biaxial
Optic Sign Negative
Polariscope Reaction Doubly Refractive (DR)
Fluorescence SWUV: Inert to weak orangy red
LWUV: Inert to weak blue or pink
Pleochroism Unobservable
Adularia Characteristic Physical Properties
Hardness 6
Streak White
Specific Gravity 2.550-2.610 Typical:2.580
Inclusions Adularia will display white or blue adularescence. Stones might have centipede like inclusions and material with aventuresence or asterism might contain reflective inclusions such as fine needles or elongated hematite platelets.
Luster Vitreous
Fracture Uneven, Splintery
Cleavage Perfect, in two directions
Adularia Chemistry & Crystallography
Chemical Name potassium aluminum silicate
Chemical Formula KAlSi3O8
Crystal System Monoclinic
Chemistry Classification Silicate

Adularia Colors

  • Blue Adularia Blue
  • White Adularia White
  • Colorless Adularia Colorless

Countries of Origin

Austria; Pakistan; India

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Tim Matthews

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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.