Sodalite

Hardness: 5.5-6 on Mohs scale. Color: Typically deep royal blue, often with white streaks of calcite or white inclusions, can also be gray, yellow, green, or pink. Luster: Vitreous to greasy. Crystal Structure: Isometric; dodecahedral crystals are rare, usually massive, granular, or in veins. Cleavage: Indistinct to poor in six directions. Specific Gravity: 2.1-2.3.

Sodalite forms in igneous rocks that are rich in soda and poor in silica, such as nepheline syenites. It crystallizes from magma at relatively low temperatures and pressures. It can also be found in metamorphic rocks that have undergone metasomatic alteration. Its geological age varies depending on the specific igneous or metamorphic event.

Sodalite is primarily used as an ornamental stone and in jewelry due to its attractive blue color. It is often carved into cabochons, beads (as seen in the image), small sculptures, and decorative objects. It's also used for facings and inlays in construction and interior design.

Sodalite is a member of the sodalite group of minerals, which also includes lazurite (a component of lapis lazuli), hauyne, and nosean. While often mistaken for lapis lazuli, sodalite typically lacks the flecks of pyrite found in lapis. The intense blue color is due to the presence of chloride ions within its structure.

In the field, sodalite can be identified by its distinctive blue color, often mottled with white calcite or other light-colored minerals. Its relative softness (scratches with a steel knife) helps differentiate it from harder blue minerals. It is commonly found in Canada (especially around Bancroft, Ontario, and around Cariboo, British Columbia), Greenland, Norway, Russia (Kola Peninsula), Brazil (Bahia), and the USA (Magnet Cove, Arkansas; Litchfield, Maine). For collectors, identifying natural specimens and distinguishing them from dyed or synthetic materials is important; a good test is sodalite's ability to glow orange under longwave UV light.