Sodalite
Sodalite (IMA name: Sodalite) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); commonly found in massive, granular, or tumbled forms rather than distinct crystals.
Mineral Group
Silicates (Subgroup: Tectosilicates, specifically the Sodalite group)
Chemical Formula
Na8(Al6Si6O24)Cl2 (Sodium Aluminum Silicate Chloride)
Formation Process
Igneous formation; crystallizes from sodium-rich magmas in silica-undersaturated rocks like nepheline syenites or phonolites.
About This Crystal
A deep royal blue to violet-blue opaque mineral. The specimen shown is tumbled and polished, displaying a vitreous luster with characteristic white or grayish streaks and mottled patches of calcite or feldspar.
Physical Characteristics
Color: Royal blue; Streak: White; Cleavage: Poor/Indistinct; Fracture: Uneven to conchoidal; Specific Gravity: 2.27–2.33; Fluorescence: Strong bright orange to red under longwave UV (LWUV).
Optical Properties
Refractive Index: 1.48 (Isotropic); Singly refractive; No pleochroism or dispersion; typically opaque to translucent on thin edges.
Hardness & Durability
Origin Region
Brazil (Bahia), Canada (Bancroft), Namibia, Russia, and Greenland. Typically found in alkaline igneous rocks.
Hardness & Durability
Mohs Hardness: 5.5 to 6. Brittle tenacity. Fair durability but susceptible to scratching by quartz (Hardness 7) and household dust.
Care & Maintenance
Clean with warm soapy water and a soft cloth. Avoid ultrasonic cleaners, steam, and harsh acids (especially hydrochloric acid which can etch it). Store separately from harder gemstones.
Rarity & Value
Relatively Common; Affordable price range. Value is determined by the depth of blue and minimal white veining. Often sold as tumbled stones, beads, or decorative carvings.
Special Characteristics
Known for its 'Hackmanite' variety which is tenebrescent (changes color in sunlight); standard sodalite is noted for its vivid orange fluorescence under UV light.
Lore & History
Discovered in Greenland in 1811; became popular after a large deposit was found in Ontario during a royal visit by Princess Margaret. Traditionally associated with the Throat and Third Eye chakras, believed to promote logic, truth, and inner peace.