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Feldspar Rough
Feldspar Classification
Common Name Feldspar
Species Feldspar

Feldspar Colors

  • Black Feldspar Black
  • White Feldspar White
  • Red Feldspar Red
  • Pink Feldspar Pink
  • Multi-color Feldspar Multi-color
  • Gray Feldspar Gray
  • Brown Feldspar Brown
  • Green Feldspar Green
  • Colorless Feldspar Colorless
  • Yellow Feldspar Yellow
  • Orange Feldspar Orange
  • Blue Feldspar Blue

Feldspar Spectra

Feldspar Spectra

Color due to iron. Many of the pale-yellow specimens of this variety of feldspar show only a weak and indistinct absorption line at 448nm. The more saturated color here shows this as a strong band accompanied by an even broader one centered at 420nm. Both bands are typical of a ferric iron spectrum

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Countries of Origin

Tanzania, United Republic Of; United States of America (the); Madagascar; India; Canada; Mongolia; Pakistan; Unknown; China; Namibia; Russian Federation (the); Brazil; Italy; Mexico

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Orthoclase Feldspar

While feldspar is one of the most abundant mineral families in the world, gem quality crystals are scarce, coveted and spectacularly beautiful, as they often possess rare optical effects. Many feldspar gems only occur in isolated deposits and are far rarer than better known gems such as diamond, ruby or sapphire. Some varieties are commonly encountered and many are seen in granites, for example, "Black Pearl" granite countertops are actually composed mostly of feldspar. While orthoclase, a potassium-rich feldspar, is better known to collectors, there is one variety that many are familiar with--moonstone, prized for its shimmering adularescence.

Orthoclase Feldspar Feldspar
Orthoclase Feldspar Classification
Common Name Orthoclase Feldspar
Orthoclase Feldspar Optical Properties
Dispersion Strength: weak fire Value: 0.12
Refractive Index 1.518-1.526
Birefringence 0.005-0.008
Fluorescence SWUV: Transparent yellow: Inert to weak reddish orange
LWUV: Transparent yellow: Inert to weak reddish orange semitranslucent white: red
Pleochroism Unobservable
Orthoclase Feldspar Characteristic Physical properties
Specific Gravity 2.55
Inclusions Orthoclase feldspar might display centipede like inclusions. Material with aventuresence or asterism might contain reflective inclusions such as fine needles or elongated hematite platelets.
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.