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 Classification
Common Name Sunstone
Species Feldspar
Sunstone Optical Properties
Transparency Semitransparent - Opaque
Refractive Index 1.539-1.547
Birefringence 0.007-0.01
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
Chemical Formula KAlSiO8
Crystal System Triclinic
Chemistry Classification Silicate

Alternate Names

Star Sunstone

Countries of Origin

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

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Species/Variety

Sunstone (Oligoclase)

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 (Oligoclase) Sunstone
Sunstone (Oligoclase) Classification
Common Name Sunstone (Oligoclase)
Sunstone (Oligoclase) Characteristic Physical properties
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.