Labradorite
Labradorite (a variety of Anorthite / Plagioclase Feldspar) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically found in massive or granular form, rarely in distinct tabular or prismatic crystals.
Mineral Group
Silicates (Tectosilicate); Feldspar group; Plagioclase series
Chemical Formula
(Na,Ca)(Al,Si)4O8 with Ca/(Ca+Na) ratio between 50% and 70%
Formation Process
Igneous formation; crystallizes in mafic igneous rocks such as basalt and gabbro, and sometimes in metamorphic rocks.
About This Crystal
An opaque to translucent dark grey-green stone with a vitreous luster. It is famous for its 'schiller' or labradorescence, which displays flashes of blue, green, and gold colors as light reflects off internal twinning planes.
Physical Characteristics
Color: Dark grey/green; Streak: White; Cleavage: Perfect in two directions; Fracture: Uneven to conchoidal; Specific Gravity: 2.68–2.72; Fluorescence: Weak red or yellow under UV.
Optical Properties
Biaxial (+); Refractive Index: 1.559–1.573; Birefringence: 0.008–0.010; Principal phenomenon: Labradorescence caused by light interference in microscopic exsolution lamellae.
Hardness & Durability
Origin Region
Madagascar, Canada (Labrador), Finland (Spectrolite variety), Russia, and Australia.
Hardness & Durability
Mohs Hardness: 6.0–6.5; Toughness: Brittle; wears well in jewelry if protected from hard strikes due to perfect cleavage.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and steam cleaning. Sensitive to sudden temperature changes and strong acids.
Rarity & Value
Common to uncommon; value is heavily determined by the intensity and spectrum of the labradorescence flashes. Spectrolite from Finland is the rarest variety.
Special Characteristics
Labradorescence (iridescent play of color), often showing 'spectral' colors; sometimes exhibits 'phantom' inclusions of magnetite or ilmenite.
Lore & History
First discovered in Labrador, Canada in 1770. Inuit lore suggests the stone contains the Northern Lights captured in rock. Traditionally used as a 'Stone of Transformation' associated with the Third Eye and Crown Chakras.