Sodalite
Sodium aluminum silicate chloride
A royal-blue feldspathoid mineral with white calcite veining, often confused with lapis lazuli but lacking its golden pyrite flecks.
- Mohs hardness
- 5.5-6
- Color
- Rich royal blue with white veining
- Type
- mineral
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Overview
Sodalite is a rich royal-blue feldspathoid mineral, a sodium aluminum silicate that also contains chlorine. It usually appears as massive blue material streaked with white veins of calcite, and it is one of the components that can occur within lapis lazuli—though as a standalone mineral it lacks lapis's golden pyrite.
Most sodalite is opaque and ornamental, but a special variety called hackmanite is famous for tenebrescence—it temporarily changes color (often pink to deep violet) after exposure to ultraviolet light, then fades back.
Named for its sodium content, sodalite is a popular, affordable blue carving and jewelry stone.
Formation & geology
Sodalite forms in silica-poor, sodium-rich igneous rocks such as nepheline syenites and phonolites, and in related pegmatites and volcanic ejecta. As a feldspathoid, it crystallizes where there is not enough silica to form ordinary feldspar.
It can also occur in contact metamorphic rocks, especially where sodium-rich fluids react with limestone, which is the same broad setting that produces lapis lazuli.
Major sources include Brazil, Canada (Bancroft, Ontario), Greenland, Namibia, and Russia (the Kola Peninsula).
How to identify it
- Color: Deep royal blue, typically with white calcite veining; some grayish or violet.
- Hardness: 5.5-6; scratched by quartz and a hard steel file.
- Streak: White; luster vitreous to greasy, often translucent on edges.
- No pyrite: A key way to separate it from lapis lazuli.
Look-alikes: Lapis lazuli is the main confusion—lapis shows golden pyrite flecks and a more uniform deep blue, while sodalite has white veining and no pyrite. Lazurite and azurite are also blue; azurite is softer and fizzes in acid. UV testing can reveal hackmanite's color change.
Uses & significance
Sodalite is a popular ornamental and lapidary stone, polished into cabochons, beads, spheres, bookends, and inlays, and used as an affordable blue alternative to lapis lazuli in jewelry and decor.
Value depends on deep, even blue color and attractive (not excessive) white veining. Hackmanite specimens are prized by collectors for their light-induced color change.
In metaphysical traditions sodalite is associated with logic, communication, and calm—cultural beliefs, not scientific fact.
Frequently asked questions
How do you tell sodalite from lapis lazuli?
Lapis lazuli has golden pyrite flecks and a deeper, more uniform blue, while sodalite shows white calcite veining and contains no pyrite.
Is sodalite valuable?
Sodalite is abundant and affordable. Value rises with deep, even blue color, good polish, and for collectors, the rare color-changing hackmanite variety.
What is hackmanite?
Hackmanite is a sodalite variety that displays tenebrescence—it temporarily darkens or changes color after UV exposure and fades back in normal light.
Can sodalite get wet?
Brief contact is fine, but it is porous and only moderately hard, so avoid prolonged water and chemicals to protect its polish and color.
Sodalite guides
In-depth guides for identifying, valuing, and understanding Sodalite.
Sodalite identified by the community
Real specimens identified with Rock Identifier.
