igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
Hardness: 5.5-6.0 Mohs; Color: Deep royal blue to denim-blue with white veining; Luster: Vitreous to greasy; Crystal Structure: Isometric; Cleavage: Poor; Specific Gravity: 2.2-2.4.
- Hardness
- 5
- Color
- Deep royal blue to denim-blue with white veining
- Luster
- Vitreous to greasy
Identified More igneous →
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Physical properties
Hardness: 5.5-6.0 Mohs; Color: Deep royal blue to denim-blue with white veining; Luster: Vitreous to greasy; Crystal Structure: Isometric; Cleavage: Poor; Specific Gravity: 2.2-2.4.
Formation & geological history
Formed in silica-poor igneous rocks such as nepheline syenites or phonolites. It can also form during contact metamorphism of calcareous rocks. Generally found across several geological eras including the Cenozoic.
Uses & applications
Used primarily as a gemstone in jewelry, for decorative carvings, and as a semi-precious ornamental stone. It has some industrial use as a source of sodium and aluminum.
Geological facts
Sodalite was first discovered by Europeans in 1811 in Greenland, but it became famous when a large deposit was found in Ontario, Canada, during a visit by the Princess of Wales, leading to the nickname 'Princess Blue'.
Field identification & locations
Identify by its rich blue color and characteristic white calcite streaks. Unlike Lapis Lazuli, it rarely contains golden pyrite inclusions. It is frequently found in geological environments where silica content is very low.
