Rock Identifier
Sodalite (Sodalite (Na8Al6Si6O24Cl2)) — mineral
mineral

Sodalite

Sodalite (Na8Al6Si6O24Cl2)

Hardness: 5.5 to 6 on Mohs scale; Color: Royal blue to deep violet-blue with white streaks; Luster: Vitreous to greasy; Crystal Structure: Isometric (cubic); Cleavage: Poor; Specific Gravity: 2.27–2.33.

Hardness
5
Color
Royal blue to deep violet-blue with white streaks
Luster
Vitreous to greasy
Identified More mineral

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Physical properties

Hardness: 5.5 to 6 on Mohs scale; Color: Royal blue to deep violet-blue with white streaks; Luster: Vitreous to greasy; Crystal Structure: Isometric (cubic); Cleavage: Poor; Specific Gravity: 2.27–2.33.

Formation & geological history

Formed in silica-poor igneous rocks such as nepheline syenites and phonolites. It typically crystallizes from alkaline magmas and can be found in Pegmatites.

Uses & applications

Used primarily in jewelry as beads and cabochons, as ornamental stone for carvings and countertops, and occasionally as a source of sodium and aluminum.

Geological facts

Sodalite is a member of the sodalite group and is named for its high sodium content. It was first discovered in Greenland in 1811 but became popular after large deposits were found in Ontario, Canada in 1891.

Field identification & locations

Identify in the field by its intense blue color and white streaks (usually calcite). Unlike Lapis Lazuli, Sodalite rarely contains gold-colored pyrite specks and has a lower specific gravity. It is frequently fluorescent under UV light.