mineral
Blue-and-yellow sodalite-bearing rock (likely sodalite in nepheline syenite)
Sodalite, Na8(Al6Si6O24)Cl2, likely mixed with feldspar and/or nepheline
AI-generated identification · may be incorrectTumbled, opaque specimen with deep royal-blue sodalite and cream-white to tan matrix; vitreous to greasy luster and massive texture. Sodalite hardness is about 5.5–6 Mohs, with poor cleavage and specific gravity near 2.3–2.4; exact properties are obscured by polishing and matrix minerals.
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Physical properties
Tumbled, opaque specimen with deep royal-blue sodalite and cream-white to tan matrix; vitreous to greasy luster and massive texture. Sodalite hardness is about 5.5–6 Mohs, with poor cleavage and specific gravity near 2.3–2.4; exact properties are obscured by polishing and matrix minerals.
Formation & geological history
Sodalite crystallizes in silica-poor, sodium-rich alkaline igneous rocks such as nepheline syenite, commonly forming in Precambrian intrusive complexes. The pictured piece is likely a polished or naturally worn fragment rather than a crystal.
Uses & applications
Used as an ornamental stone, cabochon, bead, carving material, and inexpensive jewelry stone; associated nepheline syenite is also used for aggregate and ceramics.
Geological facts
The blue color comes from sulfur- and chloride-bearing sodalite-group chemistry; white veining or patches may include calcite or feldspar. It is commonly confused with lapis lazuli, but lapis usually contains visible golden pyrite specks.
Field identification & locations
Identify by its strong blue color, cream matrix, moderate hardness, and lack of metallic pyrite sparkle; a streak, hardness, and acid test can help distinguish it from lapis. Common sources include Canada, Brazil, Namibia, and Russia.
