Hauyne
Hauyne or haüyne, also called hauynite or haüynite (/ɑːˈwiːnaɪt/ ah-WEE-nyte), is a tectosilicate sulfate mineral with endmember formula Na3Ca(Si3Al3)O12(SO4). As much as 5 wt % K2O may be present, and also H2O and Cl. It is a feldspathoid and a member of the sodalite group. Hauyne was first described in 1807 from samples discovered in Vesuvian lavas in Monte Somma, Italy, and was named in 1807 by Brunn-Neergard for the French crystallographer René Just Haüy (1743–1822). It is sometimes used as a gemstone.
| Haüyne | |
|---|---|
Hauyne from Mayen, Eifel Mts, Rhineland-Palatinate, Germany | |
| General | |
| Category | Tectosilicate, sodalite group |
| Formula (repeating unit) | Na3Ca(Si3Al3)O12(SO4) |
| IMA symbol | Hyn |
| Strunz classification | 9.FB.10 (10 ed) 8/J.11-30 (8 ed) |
| Dana classification | 76.2.3.3 |
| Crystal system | Isometric |
| Crystal class | Hextetrahedral (43m) H-M symbol (4 3m) |
| Space group | P43n |
| Unit cell | a = 9.08 – 9.13 Å; Z = 2 |
| Identification | |
| Formula mass | 1,032.43 g/mol |
| Color | Blue, white, gray, yellow, green, pink |
| Crystal habit | Dodecahedral or pseudo-octahedral |
| Twinning | Common on {111} |
| Cleavage | Distinct on {110} |
| Fracture | Uneven to conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 5 to 6 |
| Luster | Vitreous to greasy |
| Streak | Very pale blue to white |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.4 to 2.5 |
| Optical properties | Isotropic |
| Refractive index | n = 1.494 to 1.509 |
| Birefringence | None, isotropic |
| Pleochroism | None, isotropic |
| Fusibility | 4.5 |
| Solubility | Gelatinises in acids |
| Other characteristics | May fluoresce orange to pink under longwave ultraviolet light |
| References | |
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