Sodalite
Sodalite (IMA member of the Sodalite group) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); typically occurs in massive or granular form as seen in the specimen, rarely in dodecahedral crystals.
Mineral Group
Silicates; Subgroup: Tectosilicates (Feldspathoid group)
Chemical Formula
Na8(Al6Si6O24)Cl2 (Sodium Aluminum Silicate Chloride)
Formation Process
Igneous formation; crystallizes from alkali-rich, silica-deficient magmas. Often found in pegmatites and associated with alkaline volcanic environments.
About This Crystal
The specimen shows a deep royal blue color with a mottled or granular texture. It is opaque with a greasy to vitreous luster on fresh surfaces. Significant white-to-grey veining (likely calcite or feldspar) is common, though this specific piece is predominantly blue with minor pale inclusions.
Physical Characteristics
Color: Deep blue, grey, or white; Streak: White; Cleavage: Poor; Fracture: Uneven to conchoidal; Specific Gravity: 2.27–2.33; Fluorescence: Often exhibits strong orange-red fluorescence under long-wave UV light.
Optical Properties
Isotropic (Singly Refractive); Refractive Index: 1.483–1.487; Birefringence: None; typically lacks pleochroism due to its cubic nature.
Hardness & Durability
Origin Region
Bancroft (Ontario, Canada), Brazil, Namibia, Greenland, and Russia. Often found in nepheline syenites and other silica-poor igneous rocks.
Hardness & Durability
Mohs Hardness: 5.5 to 6. It is relatively brittle and sensitive to pressure and scratches compared to quartz-based minerals.
Care & Maintenance
Avoid ultrasonic cleaners and steam cleaning. Clean with warm soapy water and a soft cloth. Keep away from harsh acids and prolonged exposure to high heat. Store separately to avoid scratches from harder gems.
Rarity & Value
Relatively common and affordable. Value is determined by color intensity (vivid royal blue is preferred) and the absence of excessive white/grey matrix or calcite veining.
Special Characteristics
Known for its distinct sodic-chlorine composition. Often confused with Lapis Lazuli, but Sodalite typically lacks the golden pyrite inclusions characteristic of Lapis and has a lower specific gravity.
Lore & History
Historically discovered in Greenland in 1811; became popular in 1901 when Princess Margaret of England visited Bancroft, Ontario, and chose it for royal decoration (often called 'Princess Blue'). Traditionally associated with the Throat and Third Eye chakras, believed to promote logic, truth, and inner peace.