Rock Identifier
Polished sodalite (Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, commonly in nepheline syenite) — mineral
mineral

Polished sodalite

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, commonly in nepheline syenite

AI-generated identification · may be incorrect

Deep royal-blue, white veining or patches, vitreous to greasy luster, typically massive and polished; Mohs hardness 5.5–6, imperfect cleavage, specific gravity about 2.2–2.4. The blue color may resemble lapis lazuli, but sodalite usually lacks abundant metallic-gold pyrite.

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Physical properties

Deep royal-blue, white veining or patches, vitreous to greasy luster, typically massive and polished; Mohs hardness 5.5–6, imperfect cleavage, specific gravity about 2.2–2.4. The blue color may resemble lapis lazuli, but sodalite usually lacks abundant metallic-gold pyrite.

Formation & geological history

Forms as a sodium-rich feldspathoid mineral in alkaline igneous rocks, especially nepheline syenites; most deposits formed in Precambrian to younger alkaline complexes. The pictured piece is tumbled or polished.

Uses & applications

Used as an ornamental stone, cabochon, bead, carving material, and lapidary specimen; also collected for its vivid blue color. It has limited industrial use.

Geological facts

Sodalite is named for its relatively high sodium content. It commonly occurs with white calcite, producing the characteristic blue-and-white pattern.

Field identification & locations

Identify by its intense blue color, white calcite veining, moderate hardness, and lack of pyrite sparkle; a streak, hardness, or UV test can help distinguish it from lapis lazuli. Common sources include Canada, Brazil, Namibia, Russia, and Greenland.