Sodalite
Sodalite (IMA Member of the Sodalite Group) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Cubic (Isometric); commonly occurs in massive or granular habits rather than distinct crystals
Mineral Group
Silicates (Tectosilicate); Sodalite Group
Chemical Formula
Na8(Al6Si6O24)Cl2
Formation Process
Igneous formation; crystallizes from alkaline magmas in nepheline syenites, phonolites, and related rock types; also occurs in metasomatized calcareous rocks.
About This Crystal
Opaque to translucent material with a mottled royal blue color and characteristic white veins or patches of calcite. This specific tumbled stone shows a dull to vitreous luster with a waxy surface texture.
Physical Characteristics
Color: Royal blue, grey, white. Streak: White. Cleavage: Poor/Inconspicuous. Fracture: Uneven to conchoidal. Specific Gravity: 2.14–2.30. Fluorescence: Frequently shows strong orange to red fluorescence under longwave UV light.
Optical Properties
Refractive Index: 1.48 (Isotropic). Being cubic, it is singly refractive. It does not exhibit pleochroism or dispersion but can show a 'greasy' luster on fractured surfaces.
Hardness & Durability
Origin Region
Brazil (Bahia), Canada (Bancroft), Namibia, Russia, and Greenland. Typically found in silica-poor igneous rocks.
Hardness & Durability
Mohs Hardness: 5.5 to 6. Brittle tenacity. Fair durability but susceptible to scratching from harder gemstones like quartz or beryl.
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic cleaners and steam cleaning. Sensitive to acids and prolonged exposure to heat. Store separately to prevent scratching.
Rarity & Value
Common and affordable. Value is determined by the intensity of the blue color and the lack of distracting grey or white inclusions. Often confused with Lapis Lazuli but lacks pyrite inclusions.
Special Characteristics
Known for its 'hackmanite' variety which displays tenebrescence (color change when exposed to sunlight). Most common specimens are notable for their bright orange fluorescence.
Lore & History
Historically used as an ornamental stone; gained popularity in 1891 when deposits were found in Ontario during a royal visit. Metaphysically associated with the Throat and Third Eye chakras, believed to promote logic, truth, and inner peace.