Sunstone
Feldspar var. Sunstone (Oligoclase or Andesine) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically occurs in massive or granular habits with occasional tabular crystals.
Mineral Group
Silicates; Tectosilicate (Plagioclase Feldspar group)
Chemical Formula
(Na,Ca)AlSi3O8 with Cu or Fe2O3 inclusions
Formation Process
Igneous; forms via magmatic crystallization in volcanic rocks or pegmatites where copper or hematite plates exsolve during cooling.
About This Crystal
A translucent to opaque reddish-brown mineral with a vitreous to pearly luster. It features a distinct metallic schiller or aventurescence caused by light reflecting off tiny internal mineral inclusions.
Physical Characteristics
Color: Orange, reddish-brown, or gold; Streak: White; Cleavage: Two directions at nearly 90 degrees; Fracture: Uneven to conchoidal; Specific Gravity: 2.62-2.67; Fluorescence: Usually inert or weak red.
Optical Properties
Refractive Index: 1.537-1.553; Birefringence: 0.007-0.011; Doubly refractive; Exhibits 'aventurescence' (shimmering metallic effect from copper or hematite platelets).
Hardness & Durability
Origin Region
Oregon (USA), Norway, Tanzania, and India; typically found in basaltic lava flows or pegmatites.
Hardness & Durability
Mohs Hardness: 6.0 to 6.5; Toughness: Fair due to perfect cleavage; Wearability: Good for earrings/pendants, caution recommended for rings.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and steam cleaning; sensitive to sudden temperature changes and harsh chemicals.
Rarity & Value
Common to Uncommon; Oregon Sunstone with high copper content is rarer and more valuable; prices range from $5 to $150+ per carat depending on schiller and clarity.
Special Characteristics
Features Aventurescence (Shiller effect) and occasionally pleochroism in Oregon varieties; may contain distinct copper laths or hematite 'confetti' inclusions.
Lore & History
Historically used by Viking navigators for orientation and by indigenous peoples in the Oregon region for trade. Traditionally associated with the solar plexus chakra and believed to represent leadership and abundance.