SODALITE: Namibia (~ 2 each)
Sodalite is extremely rich in color, also quite tough and easy to cut, making it very desirable among hobbyists. Faceted gems are very lovely despite their lack of transparency because the color is so beautiful. Sodalite group minerals are also responsible for the fine color of lapis lazuli, another blue gem.
Sodalite Value
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Sodalite Information
| Data | Value |
| Name | Sodalite |
| Varieties | Hackmanite |
| Crystallography | Isometric. Crystals rare (dodecahedral); massive. granular. |
| Colors | Colorless; white, yellowish, greenish, reddish; usually light to dark blue. |
| Luster | Vitreous; greasy. |
| Hardness | 5.5-6. |
| Density | 2.14-2.4; massive blue ~2.28. |
| Cleavage | Poor. Fracture uneven to conchoidal. Brittle. |
| Dispersion | 0.018. |
| Stone Sizes | Massive blue material provides blocks for carvings, decorative objects, and cabochons or spheres to almost any desired size, especially from Canada and Namibia. Much sodalite is carved in ldar-Oberstein, Germany, made into boxes and beads. Faceted gems are sometimes cut from very translucent Namibian material, but these gems are very dark and not very transparent, except in tiny sizes (under 1 carat). |
| Luminescence | In LW, usually orangy red to violet; also dull pink in SW (Guinea). Hackmanite, from Dungannon Township, Ontario, Canada: bright pale pink in SW, bright yellow-orange in LW. Mineral is white, may turn raspberry red after exposure to SW; color fades rapidly in sunlight, and cycle is repeatable. |
| Spectral | Not diagnostic. |
| Formula | Na4Al3(SiO4)3Cl. |
Optics: Isotropic; N= 1.483-1.487.
Occurrence: ln nepheline syenites and related rock types.
Montana; South Dakota; Colorado; Arkansas; Maine; New Hampshire; Massachusetts.
Greenland; Langesundsfford, Norway; Rajasthan, India; Bahia. Brazil: USSR; Scotland; Ruma. French Guinea.
Bancroft, Ontario, Canada: massive, deep blue material, reddish streaks.
Dungannon Township, Ontario, Canada: hackmanite; also sodalite from British Columbia, other locations.
Ohopoho, northern Namibia: extremely intense, solid blue material, sometimes very translucent, almost transparent (N = 1.486).
Comments: Sodalite is extremely rich in color, also quite tough and easy to cut, making it very desirable among hobbyists. Faceted gems are very lovely despite their lack of transparency because the color is so beautiful. Sodalite group minerals are also responsible for the fine color of lapis lazuli, another blue gem.
Name: In allusion to the sodium content.
