Sodalite

Hardness: 5.5-6 on Mohs scale. Color: Typically deep blue, but can also be gray, yellow, green, or pink. Often includes white streaks or veins (calcite). Luster: Vitreous to greasy. Crystal structure: Isometric (dodecahedral or octahedral forms, but often found in massive, granular aggregates). Cleavage: Indistinct in 6 directions. Specific Gravity: 2.15-2.35. Sometimes exhibits fluorescence under UV light, glowing orange or red.

Sodalite is a tectosilicate mineral that forms in igneous rocks that crystallize from sodium-rich magmas. It is commonly found in nepheline syenites and other related intrusive and volcanic rocks. It can also be found in metamorphosed limestones. Its formation is associated with silica-undersaturated and alkali-rich geological environments. Geological age varies depending on the specific deposit, but it is typically found in formations that are millions to hundreds of millions of years old.

Sodalite is primarily used as an ornamental stone and in jewelry due to its attractive blue color. It is carved into cabochons, beads (as seen in the image), small sculptures, and decorative objects. Larger pieces are used for tabletops or other architectural applications. It is less commonly used in industry due to its relative softness.

Sodalite is part of the sodalite group of minerals, which also includes hauyne, nosean, and lazurite. It was first discovered in Greenland in 1806 and later gained popularity when large deposits were found in Ontario, Canada, and then in Brazil. Sodalite can sometimes be mistaken for lapis lazuli, but lapis lazuli is a rock composed of several minerals (including lazurite, calcite, and pyrite) and often contains visible flecks of golden pyrite, which sodalite typically lacks. The name 'sodalite' reflects its sodium content.

In the field, sodalite is identified by its distinctive blue color, relatively low hardness (easily scratched by a steel file), and often interspersed white calcite veins. It does not react with hydrochloric acid unless the white veins are calcite. It commonly occurs in association with other alkali minerals. Major deposits are found in Brazil (Bahia state, where some of the finest blue sodalite comes from), Namibia (near Swakopmund), Canada (Bancroft, Ontario), India, Afghanistan, Russia (Urals), and other locations. When collecting, look for massive blue formations in alkali-rich igneous or metamorphic rocks. Dealers sometimes call it 'Poor Man's Lapis' due to its similar appearance to lapis lazuli but lower cost.