mineral
Tumbled sodalite
Sodalite, Na8(Al6Si6O24)Cl2, commonly occurring in nepheline-syenite rocks
AI-generated identification · may be incorrectUsually deep blue to blue-gray with white calcite veining, vitreous to greasy luster, and an imperfect cleavage; Mohs hardness 5.5–6, cubic crystal system, specific gravity about 2.2–2.4. The rounded shape and shine indicate tumbling or polishing.
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Physical properties
Usually deep blue to blue-gray with white calcite veining, vitreous to greasy luster, and an imperfect cleavage; Mohs hardness 5.5–6, cubic crystal system, specific gravity about 2.2–2.4. The rounded shape and shine indicate tumbling or polishing.
Formation & geological history
Forms as a feldspathoid mineral in silica-poor, sodium-rich igneous rocks such as nepheline syenite, generally in alkaline intrusive complexes. Important deposits occur in Canada, Brazil, Namibia, and Russia; individual specimens may range from Precambrian to younger igneous ages.
Uses & applications
Used as an ornamental stone, beads, cabochons, carvings, and lapidary material; fine blue pieces are sometimes sold as inexpensive gemstone substitutes for lapis lazuli.
Geological facts
The specimen’s uniform blue-gray color and cloudy white patches are consistent with sodalite, though image quality prevents certain distinction from blue calcite or dyed stone. Unlike lapis lazuli, sodalite typically lacks abundant metallic-gold pyrite flecks.
Field identification & locations
Identify by its blue color, white veining, moderate hardness, and lack of strong reaction to dilute acid; a streak test should be pale blue/white. Common tumbled pieces are widely sold in metaphysical and mineral shops.
