Rock Identifier
Sodalite (Sodalite (Na8(Al6Si6O24)Cl2)) — mineral
mineral

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Hardness: 5.5-6 (Mohs scale); Color: Royal blue to gray, often with white streaks; Luster: Vitreous; Crystal Structure: Isometric; Cleavage: Poor; Specific Gravity: 2.27-2.33

Hardness
5
Color
Royal blue to gray, often with white streaks
Luster
Vitreous
Identified More mineral

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Physical properties

Hardness: 5.5-6 (Mohs scale); Color: Royal blue to gray, often with white streaks; Luster: Vitreous; Crystal Structure: Isometric; Cleavage: Poor; Specific Gravity: 2.27-2.33

Formation & geological history

Formed in silica-poor igneous rocks such as nepheline syenites and phonolites. It can also occur in contact metamorphic rocks such as marbles. Most deposits date from the Precambrian to Cenozoic eras.

Uses & applications

Used primarily as an ornamental stone, for jewelry (cabochons and beads), and as a collector's specimen. In industry, it was historically used as a source of pigment.

Geological facts

Sodalite is often confused with Lapis Lazuli, but unlike Lapis, Sodalite rarely contains pyrite specks and is significantly lighter in weight. It is known for its strong orange fluorescence under long-wave UV light.

Field identification & locations

Identify in the field by its distinct royal blue color, greasy luster on fresh surfaces, and lack of pyrite. It is commonly found in Bancroft (Ontario), Brazil, Greenland, and Namibia.