Sunstone

saf-ahyuh r

A gem known since ancient times, sunstone is a type of feldspar formed and crystallized in lava flows. Radiating with the power of eternal light, sunstone has been reportedly found in the tombs of Viking sailors who believed it would aid in their journey through both life and the afterlife. A distinguishing feature of sunstone is its metallic schiller, which rolls across the stone's surface. The effect is due to the presence of small plate-like inclusions of minerals such as hematite or native copper. These inclusions interfere with the passage of light, causing it to scatter. If the inclusions are larger and visible to the eye, they create glittery star-like reflections that gemologists refer to as aventurescence.

Sunstone Polished
Sunstone Classification
Common Name Sunstone
Species Feldspar
Sunstone Optical Properties
Transparency Semitransparent - Opaque
Refractive Index 1.518-1.572
Birefringence 0.005- 0.009
Optic Character Biaxial
Optic Sign Negative
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism Unobservable
Sunstone Characteristic Physical Properties
Hardness 6
Specific Gravity 2.620-2.670 Range:0.02/-0.03 Typical:2.650
Toughness Poor
Inclusions Sunstones contain tiny reddish to golden or green platelets of hematite or goethite. Stones might show a four-rayed star with slivery adularescence if fine needles intersect.
Luster Vitreous
Stability Good
Fracture Uneven, Splintery
Cleavage Perfect, in two directions
Sunstone Chemistry & Crystallography
Chemical Name calcium aluminum silicate or potassium aluminum silicate
Chemical Formula KAlSi3O8 or (Ca,Na)(Al,Si)2Si2O8

Crystal System NA
Chemistry Classification Silicate

Sunstone Colors

  • Multi-color Sunstone Multi-color
  • Yellow Sunstone Yellow
  • Red Sunstone Red
  • Orange Sunstone Orange
  • Green Sunstone Green
  • Brown Sunstone Brown
  • Bi-color Sunstone Bi-color

Alternate Names

Oregon Sunstone; Aventurescent Feldspar; Orthoclase Sunstone; Star Sunstone; Oligoclase Sunstone; Labradorite Sunstone

Countries of Origin

Tanzania, United Republic Of; Colombia; United States of America (the); Unknown; China; Congo (the); Brazil; Mexico; South Africa; Germany; India

Care

Normal, gentle handling. Avoid ultrasonic cleaners.

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Species/Variety

Sunstone (Labradorite)

Labradorite sunstone was only thought to be found in Eastern Oregon until 2015 when a variety labradorite-bytownite feldspar was discovered in the Afar region of Ethiopia. The three Oregon mines are the Dust Devil, Ponderosa and the Sunstone Butte. Stones can be near-colorless, green, red, yellow or combinations of these colors. The stones have tiny copper platelet inclusions that cause schiller or adventurescence.

Sunstone (Labradorite) Sunstone
Sunstone (Labradorite) Classification
Common Name Sunstone (Labradorite)
Sunstone (Labradorite) Optical Properties
Refractive Index 1.563-1.572
Sunstone (Labradorite) Characteristic Physical properties
Specific Gravity 2.67
Inclusions Oregon sunstone contain tiny orange or yellow copper platelets or hematite platelets and stones might display adventurescence. Parting is common in this material.

Sunstone (Oligoclase)

Oligoclase sunstone contains hematite inclusions that catch the light. Oligoclase sunstone is called "aventurescent feldspar" when inclusions are large and produce sparkling reflections. India is a source for this type of sunstone. Oligoclase sunstone will have a slightly high refractive index than Orthoclase sunstone.

Sunstone (Oligoclase) Sunstone
Sunstone (Oligoclase) Classification
Common Name Sunstone (Oligoclase)
Sunstone (Oligoclase) Optical Properties
Refractive Index 1.539-1.547
Sunstone (Oligoclase) Characteristic Physical properties
Specific Gravity 2.65
Inclusions Sunstones contain tiny reddish to golden or green platelets of hematite or goethite. Stones might show a four-rayed star with slivery adularescence if fine needles intersect.

Sunstone (Orthoclase)

Orthoclase sunstone is one of the aventurescent feldspar varieties. Some of the best orthoclase sunstone comes from the Hart’s Range area in Australia. In the trade this material is called “rainbow lattice sunstone”. This material contains hematite and ilmenite platelets and shows rainbow interference colors. Oregon also produces “Oregon Cinnamon Sunstone” that contains hematite platelets. Orthoclase sunstone will have a slightly lower Refractive index than the oligoclase variety of sunstone.

Sunstone (Orthoclase) Sunstone
Sunstone (Orthoclase) Classification
Common Name Sunstone (Orthoclase)
Sunstone (Orthoclase) Optical Properties
Refractive Index 1.518-1.526
Sunstone (Orthoclase) Characteristic Physical properties
Specific Gravity 2.58
Inclusions Sunstones contain tiny reddish to golden or green platelets of hematite or goethite. Stones might show a four-rayed star with slivery adularescence if fine needles intersect.
Tim Matthews

Author

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.