Sodalite
Sodalite (IMA-approved mineral name) · Semi-Precious Gemstone and Decorative Stone.
Crystal System
Cubic (Isometric); typically occurs as massive or granular aggregates, rarely as dodecahedral crystals.
Mineral Group
Silicates (Tectosilicates); specifically the Feldspathoid group.
Chemical Formula
Na8(Al6Si6O24)Cl2
Formation Process
Igneous formation; crystallizes from alkali-rich magmas in silica-poor environments. Often occurs in nepheline syenites and pegmatites.
About This Crystal
The specimen is a tumbled, polished stone featuring a deep royal blue body color with significant white veining (likely calcite). It is opaque with a vitreous to greasy luster. The surface shows a smooth, rounded habit characteristic of mechanical tumbling.
Physical Characteristics
Color: Royal blue with light blue and white streaks; Streak: White; Cleavage: Poor; Fracture: Uneven to conchoidal; Specific Gravity: 2.27–2.33; Fluorescence: Often shows strong orange-red fluorescence under LW UV.
Optical Properties
Isotropic (Singly Refractive) due to cubic system; Refractive Index: 1.483–1.487; Lack of pleochroism or dispersion; no optical phenomena like chatoyancy.
Hardness & Durability
Origin Region
Major sources include Brazil, Canada (Bancroft, Ontario), Namibia, Russia, and Greenland. Typically found in alkaline igneous rocks.
Hardness & Durability
Mohs Hardness: 5.5 to 6; Toughness: Poor to Fair (brittle). It is softer than quartz and can be scratched by steel; suitable for low-wear jewelry like pendants.
Care & Maintenance
Clean with warm soapy water only; avoid ultrasonic cleaners and steam cleaning. Sensitive to acids and household chemicals. Store separately to prevent scratching from harder stones.
Rarity & Value
Common and affordable. Value is determined by the richness of blue color and the aesthetic pattern of the white inclusions. Generally untreated, though some material is dyed to mimic higher-grade lapis lazuli.
Special Characteristics
Notable for its intense blue color without the pyrite inclusions found in Lapis Lazuli. Frequently exhibits a 'tenebrescene' variety called Hackmanite (though not evident in this specimen).
Lore & History
Discovered in Greenland in 1811; gained popularity after the Princess of Wales visited Canada in 1901. Traditionally called the 'Poet's Stone' or 'Stone of Logic,' associated with clarity of thought and the throat chakra.