Labradorite
Labradorite (Plagioclase Feldspar series) · Semi-Precious Gemstone / Collector Mineral
Crystal System
Triclinic; typically found in massive, granular, or tabular forms; rare distinct crystals
Mineral Group
Silicates (Tectosilicates); Feldspar Group; Plagioclase Series
Chemical Formula
(Ca, Na)(Al, Si)4O8 with traces of iron and magnesium
Formation Process
Igneous formation; crystallizes from cooling magma primarily in mafic rocks like basalt or gabbro; often found in anorthosites
About This Crystal
An opaque to translucent dark gray-green to black mineral that exhibits a spectacular play of iridescent colors known as labradorescence. It has a vitreous to pearly luster and often shows internal twinning planes.
Physical Characteristics
Color: Dark gray to gray-black; Streak: White; Cleavage: Perfect in two directions at nearly 90 degrees; Fracture: Conchoidal to uneven; Specific Gravity: 2.68–2.72; Fluorescence: Weak yellow or red under UV light
Optical Properties
Biaxial (+); Refractive Index: 1.559–1.573; Birefringence: 0.008–0.010; Labradorescence: Interference of light reflected from microscopic exsolution lamellae
Hardness & Durability
Origin Region
Madagascar, Labrador (Canada), Finland (Spectrolite variety), Russia, and Australia
Hardness & Durability
Mohs Hardness: 6.0–6.5; Toughness: Brittle to fair; Stability: Sensitive to sudden temperature changes and pressure due to perfect cleavage
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic and steam cleaners; protect from hard knocks and household chemicals; store separately to prevent scratching
Rarity & Value
Common globally, but high-quality specimens with vivid multicolor labradorescence are uncommon. Values range based on brightness of flash, rarity of color (purple/red is rarest), and transparency
Special Characteristics
Labradorescence (the 'Schiller' effect); some specimens show schiller and aventurescence simultaneously; rare varieties like Spectrolite show the full spectrum
Lore & History
Discovered in 1770 on Paul's Island, Labrador. Inuit legends say the Northern Lights were trapped inside the rocks. Historically used as a 'stone of transformation' and associated with the Third Eye and Crown chakras in traditional healing lore.