Sodalite
Sodalite · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); typically occurs in massive, granular, or tumbled forms rather than distinct crystals.
Mineral Group
Silicates (Tectosilicate); specifically a member of the Sodalite group within the Feldspathoid family.
Chemical Formula
Na8(Al6Si6O24)Cl2
Formation Process
Found in silica-poor igneous rocks such as nepheline syenites and phonolites, as well as in contact metamorphic zones.
About This Crystal
Deep Royal Blue body color with characteristic white to grayish-white veining or mottling caused by included Calcite. Displays a vitreous to greasy luster, is opaque to translucent, and shows a compact, massive texture.
Physical Characteristics
Color: Deep blue with white streaks; Streak: White; Cleavage: Poor; Fracture: Uneven to conchoidal; Specific Gravity: 2.27–2.33; Fluorescence: Strong orange/pink under Longwave UV.
Optical Properties
Refractive Index: 1.483–1.487; Single refraction (isotropic); No pleochroism; Typically lacks optical phenomena like chatoyancy.
Hardness & Durability
Origin Region
Notable sources include Brazil (Bahia), Canada (Bancroft, Ontario), Namibia, and Russia (Kola Peninsula).
Hardness & Durability
Mohs Hardness: 5.5 to 6; Fair toughness; Brittle. It is softer than quartz and can be scratched by steel or harder stones.
Care & Maintenance
Clean with warm, soapy water and a soft cloth; avoid ultrasonic cleaners and steam. Sensitive to acids (HCl) and extreme heat. Store separately to avoid scratching.
Rarity & Value
Relatively common; affordable price range. Value is based on color depth and the aesthetic balance of the blue against the white calcite inclusions.
Special Characteristics
Known for strong orange-red fluorescence under UV light. It is often mistaken for Lapis Lazuli, but Sodalite lacks the golden pyrite inclusions common in Lapis.
Lore & History
Discovered in Greenland in 1811; gained popularity in 1901 when Princess Margaret of England visited Bancroft, Canada and chose the stone for interior decoration. In lore, it is called the 'Logic Stone' and associated with the Throat and Third Eye chakras.