mineral

Tumbled blue sodalite

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

AI-generated identification · may be incorrect

Dark navy-blue, opaque, glassy to greasy luster with faint white veining; Mohs hardness 5.5–6, cubic crystal system, poor cleavage, and specific gravity about 2.25–2.35. The rounded shape indicates mechanical tumbling and polishing.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-poor, sodium-rich igneous rocks such as nepheline syenite, crystallizing mainly in alkaline intrusive environments. Most specimens are Precambrian to younger, depending on locality.

Uses & applications

Used as an ornamental stone, beads, cabochons, carvings, and lapidary material; fine blue pieces are collected and occasionally used as a less expensive alternative to lapis lazuli.

Geological facts

The color comes primarily from sulfur-related defects in the crystal structure. This specimen could also be dyed dark blue material, though its appearance is consistent with polished sodalite.

Field identification & locations

Common sources include Canada, Brazil, Namibia, Russia, and Afghanistan. Distinguish it from lapis lazuli by its generally uniform blue color and lack of abundant metallic-gold pyrite; calcite or acid testing is best avoided on polished specimens.