Labradorite
Labradorite (Feldspar variety) · Semi-Precious Gemstone / Collector Mineral
Crystal System
Triclinic; typically occurs in massive or granular forms with distinct lamellar twinning.
Mineral Group
Silicates; Tectosilicates; Plagioclase Feldspar Group
Chemical Formula
(Ca, Na)(Al, Si)4O8
Formation Process
Igneous; forms via crystallization from mafic igneous rocks like basalt or gabbro; also found in some metamorphic rocks.
About This Crystal
Opaque to translucent gray-green or dark gray base color featuring a vitreous to pearly luster. Exhibits structural 'Labradorescence' flashes of blue, gold, and green.
Physical Characteristics
Body color is dark gray; streak is white; perfect cleavage in two directions; conchoidal to uneven fracture; specific gravity 2.68-2.72; weak yellow fluorescence.
Optical Properties
Refractive Index 1.560 to 1.572; Birefringence 0.008-0.010; Tri-directional pleochroism; notably displays Labradorescence due to light diffraction in lamellar layers.
Hardness & Durability
Origin Region
Notable sources include Paul's Island (Labrador, Canada), Madagascar (blue flashes), Finland (Spectrolite), and Russia.
Hardness & Durability
Mohs Hardness: 6.0 to 6.5; Toughness is poor to fair due to perfect cleavage; sensitive to pressure and rapid temperature changes.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and steam; store separately to prevent scratches from harder stones like quartz.
Rarity & Value
Commonly available; value increases with the intensity, variety of colors, and surface coverage of the labradorescence; Spectrolite from Finland is the rarest variety.
Special Characteristics
Labradorescence (Schiller effect) caused by internal twinning lamellae; some specimens show 'phantom' layers or schiller inclusions.
Lore & History
Discovered in 1770 in Labrador, Canada; Inuit lore describes it as the northern lights captured in stone. Used for protection and intuition in modern crystal healing.