| Sodalite | |
|---|---|
 | |
| General | |
| Category | Tectosilicates without zeolitic H2O |
| Formula (repeating unit) | Na 8(Al 6Si 6O 24)Cl 2 |
| IMA symbol | Sdl[1] |
| Strunz classification | 9.FB.10 |
| Crystal system | Cubic |
| Crystal class | Hextetrahedral (43m) H–M symbol: (4 3m) |
| Space group | P43n |
| Unit cell | a = 8.876(6) Å; Z = 1 |
| Identification | |
| Color | Rich royal blue, green, yellow, violet, white veining common |
| Crystal habit | Massive; rarely as dodecahedra |
| Twinning | Common on {111} forming pseudohexagonal prisms |
| Cleavage | Poor on {110} |
| Fracture | Conchoidal to uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 5.5–6 |
| Luster | Dull vitreous to greasy |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.27–2.33 |
| Optical properties | Isotropic |
| Refractive index | n = 1.483 – 1.487 |
| Ultraviolet fluorescence | Bright red-orange cathodoluminescence and fluorescence under LW and SW UV, with yellowish phosphorescence; may be photochromic in magentas |
| Fusibility | Easily to a colourless glass; sodium yellow flame |
| Solubility | Soluble in hydrochloric acid and nitric acid |
| References | [2][3][4][5] |
| Major varieties | |
| Hackmanite | Tenebrescent; violet-red or green fading to white |
Sodalite (/ˈsoʊ.dəˌlaɪt/ SOH-də-lyte) is a tectosilicate mineral with the formula Na
8(Al
6Si
6O
24)Cl
2, with royal blue varieties widely used as an ornamental gemstone. Although massive sodalite samples are opaque, crystals are usually transparent to translucent. Sodalite is a member of the sodalite group with hauyne, nosean, lazurite and tugtupite.
The people of the Caral culture traded for sodalite from the Collao altiplano.[6] First discovered by Europeans in 1811 in the Ilimaussaq intrusive complex in Greenland, sodalite did not become widely important as an ornamental stone until 1891 when vast deposits of fine material were discovered in Ontario, Canada.
- ^ Warr, Laurence N. (June 2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Mindat with locations
- ^ Webmineral data
- ^ Handbook of Mineralogy
- ^ Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
- ^ Sanz, Nuria; Arriaza, Bernardo T.; Standen, Vivien G., eds. (2015). The Chinchorro culture: a comparative perspective, the archaeology of the earliest human mummification. UNESCO Publishing. p. 162. ISBN 978-92-3-100020-1.