Tough, easy to cut or carve, and rich in color, typically blue, sodalite is highly desired by hobbyists. Even stones that lack transparency make lovely faceted gems.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Isometric. Crystals rare (dodecahedral); massive. granular.|
|Colors||Colorless; white, yellowish, greenish, reddish; usually light to dark blue.|
|Fracture||Uneven to conchoidal. Brittle.|
|Hardness||5.5 - 6|
|Specific Gravity||2.14-2.4; massive blue ~ 2.28.|
|Luminescence||In LW, usually orangy red to violet; also dull pink in SW (Guinea). See "Identifying Characteristics" below.|
|Transparency||Transparent (colorless specimens) to opaque.|
|Optics||Isotropic; N= 1.483-1.487.|
|Etymology||Named in allusion to the sodium content.|
|Occurrence||In nepheline syenites and related rock types.|
|Inclusions||White calcite in veins and patches.|
Hackmanite, a sulfur-rich variety of sodalite, shows tenebrescence. When first mined, stones from Canada and Greenland can range from pink to violet. In sunlight, however, they fade to grayish white or white. On the other hand, hackmanites from Afghanistan and Myanmar start white but turn pink or violet in sunlight. Darkness will reverse these effects.
Hackmanite from Dungannon Township, Ontario, Canada will luminesce bright pale pink in shortwave (SW) ultraviolet light. In longwave, it luminesces bright yellow-orange. Stones may turn raspberry red after exposure to SW.
Laboratories have synthesized sodalites. Since the natural gems aren’t rare, no real market for them exists. However, sodalites, natural or synthetic, can simulate other blue gems, such as lapis lazuli. Although sodalite can contain white calcite inclusions like lapis, you can distinguish them by sodalite’s lack of pyrite inclusions.
Other popular blue gem materials, like azurite, lazulite (no relation to lazurite), and turquoise, typically show different shades of blue than sodalite. However, if the colors seem close, these stones react differently to ultraviolet testing.
White sodalites may receive dye treatments to turn them into the more popular blue gems.
Canada produces large amounts of gem-quality material. Bancroft, Ontario turns out massive, deep blue material with reddish streaks. Many provinces, including British Columbia, contain sources.
Ohopoho, Namibia yields extremely intense, solid blue material that’s sometimes very translucent, almost transparent (N = 1.486).
Other notable gem-quality sites include:
- Arkansas; Colorado; Maine; Massachusetts; Montana; New Hampshire; South Dakota.
- Afghanistan; Bahia, Brazil; Greenland; Ruma, Guinea; Rajasthan, India; Myanmar; Langesundsfford, Norway; Russia; Scotland.
Lapidaries in Idar-Oberstein, Germany create many sodalite boxes and beads.
Gem cutters sometimes facet very translucent Namibian material. However, these beautiful gems are still very dark and not very transparent, except in sizes under 1 carat.
Sodalites are tough but scratch easily due to their relatively low hardness (5.5 – 6). Other popular jewelry stones, like quartz and topaz, will scratch them. (So will household dust, over time, with a hardness of 7 – 7.5). Store any sodalite jewelry separately from other pieces to avoid contact scratches. Use protective settings for ring wear. Necklace and earring use should pose fewer risks. Clean these gems only with a soft brush, mild detergent, and warm water. Consult our gemstone jewelry cleaning guide for more recommendations.