Sodalite
Sodalite (IMA member of the Sodalite group) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); typically occurs in massive, granular, or tumbled forms rather than distinct crystals.
Mineral Group
Silicates (Tectosilicates / Feldspathoids)
Chemical Formula
Na8(Al6Si6O24)Cl2
Formation Process
Igneous formation; it crystallizes from sodium-rich magmas in alkaline environments such as nepheline syenites or phonolites.
About This Crystal
A deep royal blue to violet-blue opaque mineral often mottled with white streaks or patches of calcite. The pictured specimen is a polished tumbled stone with a vitreous to greasy luster.
Physical Characteristics
Blue body color with white patches; white streak; poor cleavage in six directions (rarely visible in tumbled stones); conchoidal to uneven fracture; specific gravity 2.27–2.33; often displays orange or pink fluorescence under longwave UV light.
Optical Properties
Isotropic (singly refractive); refractive index approximately 1.48; lacks pleochroism and dispersion due to its opaque to translucent nature in bulk form.
Hardness & Durability
Origin Region
Prominently sourced from Canada (Bancroft, Ontario), Namibia, Brazil, Greenland, and Russia. Found in silica-poor igneous rocks.
Hardness & Durability
Mohs hardness of 5.5 to 6.0. It is moderately brittle and softer than quartz, making it susceptible to scratches if not handled carefully.
Care & Maintenance
Clean with warm soapy water and a soft cloth; avoid ultrasonic cleaners, steam, and harsh acids. Store away from harder gems like sapphires or diamonds to prevent surface scratching.
Rarity & Value
Common and affordable. Value is determined by the richness of the blue color and the aesthetic balance of white inclusions. Rarely treated, though some poor quality material may be dyed.
Special Characteristics
Known for its distinct sodic content and lack of pyrite (distinguishing it from Lapis Lazuli); often exhibits tenebrescence (color change upon light exposure) in specific varieties like Hackmanite.
Lore & History
Discovered in Greenland in 1811 but became popular after the Princess of Wales visited Ontario in 1901. Traditionally associated with the Throat and Third Eye chakras, believed to promote logic, truth, and inner peace.