Labradorite (Feldspar)
Anorthite (Intermediate Feldspar) · Semi-Precious Gemstone / Collector Mineral
Crystal System
Triclinic; typically occurs in massive, granular, or blocky habits; individual crystals are rare and tabular.
Mineral Group
Silicates (Tectosilicates); Plagioclase Feldspar Group
Chemical Formula
(Na,Ca)(Al,Si)4O8 with Ca/(Ca+Na) between 50-70%
Formation Process
Igneous; forms through the crystallization of mafic or intermediate magmas (such as basalt or gabbro) and in some metamorphic rocks.
About This Crystal
A dark gray to blackish-blue base color with a characteristic iridescent play of color. It is typically translucent to opaque with a vitreous to pearly luster and visible cleavage planes.
Physical Characteristics
Gray to dark gray body color; white streak; perfect cleavage in two directions; conchoidal to uneven fracture; specific gravity 2.68-2.72; occasionally fluorescent under UV.
Optical Properties
Biaxial (+/-); RI 1.559-1.573; features Labradorescence, an interference effect caused by light reflecting off microscopic exsolution lamellae within the crystal structure.
Hardness & Durability
Origin Region
Labrador (Canada), Madagascar, Finland (Spectrolite variety), Russia, and Australia; occurs in mafic igneous rocks.
Hardness & Durability
Mohs hardness 6 to 6.5; brittle toughness; sensitive to pressure and high heat; good for jewelry with protective settings.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and steam cleaning; store separately to prevent scratching from harder gems like quartz.
Rarity & Value
Common globally; value increases with the intensity, range, and regularity of the 'flash' color; Spectrolite from Finland is the most valuable variety.
Special Characteristics
Exhibits Labradorescence (iridescence); may show schiller effect; some rare specimens contain 'phantom' growth layers or metallic-looking inclusions.
Lore & History
First discovered in 1770 in Labrador, Canada; Inuit lore claims the Northern Lights were trapped inside the stones. Traditionally associated with the Third Eye and Crown chakras.