mineral
Tumbled dark-blue stone, possibly sodalite or dyed stone
Likely sodalite (Na₈Al₆Si₆O₂₄Cl₂); exact identification requires testing
AI-generated identification · may be incorrectOpaque navy-blue, rounded and polished, with faint lighter mottling; likely Mohs 5.5–6, vitreous to waxy luster, no visible cleavage, granular crystal structure, and specific gravity around 2.2–2.4.
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Physical properties
Opaque navy-blue, rounded and polished, with faint lighter mottling; likely Mohs 5.5–6, vitreous to waxy luster, no visible cleavage, granular crystal structure, and specific gravity around 2.2–2.4.
Formation & geological history
If sodalite, it formed in silica-poor, sodium-rich alkaline igneous rocks such as nepheline syenite, generally in relatively young igneous complexes. The smooth shape indicates human tumbling and polishing; dyeing or another blue stone cannot be excluded visually.
Uses & applications
Used primarily for inexpensive cabochons, beads, carvings, and lapidary specimens; it has little industrial or construction use.
Geological facts
Sodalite’s intense blue color may resemble lapis lazuli, but sodalite typically lacks abundant metallic-gold pyrite flecks. A white streak or hardness test can help distinguish it from softer dyed materials.
Field identification & locations
Common sources include Canada, Brazil, Namibia, and Russia. Check for uniform dye concentration in cracks, test streak on unglazed ceramic, and avoid destructive testing on valuable pieces.
