Labradorite (in Granite/Anorthosite matrix)
Plagioclase Feldspar var. Labradorite · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically occurs as massive, tabular, or granular aggregates within igneous rock
Mineral Group
Silicates; Tectosilicates (Feldspar Group)
Chemical Formula
(Ca,Na)(Al,Si)4O8 (specifically 50-70% Anorthite)
Formation Process
Igneous formation; crystallizes from cooling mafic magma in plutonic environments like gabbro or norite
About This Crystal
A dark, grayish-black base mineral showing an iridescent 'play of color' known as labradorescence. Shows a vitreous to pearly luster on cleavage faces with sub-metallic coppery flashes.
Physical Characteristics
Color: Gray to black; Streak: White; Cleavage: Two directions at nearly 90 degrees; Fracture: Uneven/Conchoidal; SG: 2.68-2.72; often shows lamellar twinning lines
Optical Properties
Biaxial (+/-); RI: 1.559-1.573; notable for Labradorescence caused by light interference in microscopic exsolution lamellae
Hardness & Durability
Origin Region
Labrador (Canada), Madagascar, Finland (as Spectrolite), and Russia; found in mafic igneous rocks
Hardness & Durability
Mohs Hardness: 6.0 - 6.5; brittle toughness; sensitive to pressure and high heat; good for guarded jewelry settings
Care & Maintenance
Avoid ultrasonic and steam cleaners; clean with warm soapy water and a soft cloth; store away from harder stones like quartz or topaz
Rarity & Value
Common globally, but high-quality specimens with 'full spectrum' flash are more valuable; generally affordable; rarely treated
Special Characteristics
Schiller effect (Labradorescence) displaying metallic tints of blue, green, and copper-orange as seen in the provided image
Lore & History
First discovered in Labrador in 1770; Inuit lore describes it as the Northern Lights trapped in stone. Traditionally associated with the Third Eye chakra and transformation.