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| Formula | Sodalite Na8Al6Si6O24Cl2, nosean Na8Al6Si6O24SO4, haüyne (Na,Ca)4-8Al6Si6(SO4)1-2 |
| | Optic class & sign | Isotropic |
| | Relief | Moderate, negative |
| | Refractive Index | 1.460 -1.509
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| n increases with increasing Ca and SO4 |
| | Birefringence | Zero; slight birefringence may be observed |
| | Colour | Sodalite, nosean: colourless to pale grey-blue; haüyne: commonly blue; concentric or patchy colour zoning may be present |
| | Zoning | |
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| Form | Habit | Granular |
| | | Surface | Euhedral dodecahedra in volcanics, phenocrysts may be partly resorbed; anhedral in plutonic rocks |
| | Cleavage | {110} poor |
| | Twinning | {111}, can only be recognized from external shapes |
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| Reaction textures | |
| | Alteration / decomposition | Fibrous zeolites (natrolite, thompsonite), clay minerals, cancrinite
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| Occurence | Ign | Silica-undersaturated alkaline rocks like phonolites, alkali basalts and trachytes; sodalite also in plutonic rocks, such as nepheline syenites and related rocks |
| | | Met | Sodalite: metasomatic zones in carbonate rocks; lazurite in impure marble |
| | | Sed | |
| | | Hyd | |
| | | Other | |
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| Distinctive properties | Isotropic, relief, occurrence, blue colour of haüyne |
| | Additional comments | Nosean and haüyne commonly have small inclusions; these may show a concentric arrangement. Properties listed above also include lazurite, (Na,Ca)8Al6Si6O24(SO4,S,Cl)2 |
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