Haüyne - Encyclopedia

    Class : Silicates
    Subclass : Tectosilicates
    Crystal system : Cubic
    Chemistry : Na3Ca(Si3Al3)O12(SO4)
    Rarity : Quite common

Haüyne (or haüynite) is a fairly common accessory mineral from the feldspathoid group. Its atomic structure is identical to that of sodalite and has large gaps in which Ca, Na ions, SO4 groups, and sometimes chlorine ions are housed. It is a mineral typical of alkaline lavas deficient in silica : phonolites, sometimes undersaturated basalts (with leucite, nepheline and augite), or trachytes (with sanidine). It was named in honor of Abbot René Just Haüy, creator of crystallography and who was Professor at the Natural History Museum of Paris. Haüyne rarely occurs in corroded octahedral crystals, exceptionally tetrahedral, but more often in rounded grains giving the appearance of molten crystals. Well-formed rhomboidal dodecahedral crystals are very rare. Its sky blue to bright blue color, sometimes greenish gray or bluish white, sometimes makes it difficult to distinguish from nauseane. It is exceptionally cut for jewelry.

Main photo : Haüyne from In den Dellen quarries, Mendig, Germany © Volker Betz

Haüyne from In den Dellen quarries, Mendig, Germany © Volker Betz
Twinned haüyne from In den Dellen, Mendig, Germany © Gianfranco Ciccolini
Gonnardite pseudomorph after haüyne from Sar-e-Sang, Afghanistan © Mark Mauthner
0.08 ct cut haüyne from the Eifel, Germany

Haüyne in the World

The basalt lavas of the Eifel (district of Mayen, Lake Laacher) produce splendid sky blue crystals with blunt edges measuring up to 3 cm, of gemmy quality, counting among the best specimens in the world. Magnificent centimeter-sized dark blue crystals, with a corroded appearance and partially replaced by white gonnardite come from the Afghan site of Sar-e-Sang, where the world's most beautiful lapis lazuli are also extracted. The basalts of Ariccia, in the Albani Mountains (Italy) yielded free pale blue crystals of 15 mm with perfect shapes until 1978.

Haüyne in France

In France, the ordanchite of Mont Chaumeil, near Murat (Cantal) contains small millimetric crystals of haüyne, as the tephrites of the Mont Dore Massif (Puy-de-Dôme). It is also reported in Charolles (Saône-et-Loire), Montbrison (Loire) and the Col de l'Escrinet and the Coiron plateau (Ardèche). The Tahitian basalts of Taiarapu are rich in blunt crystals of up to 3.5 cm.


A twin is known on {111}.

Fakes and treatments

No fakes recorded for this mineral species. Easy to confuse with other feldspathoids such as lazurite, nauseane or afghanite with which it sometimes shares deposits.

Hardness : 5.5 to 6
Density : 2.44 to 2.5
Fracture : Irregular
Streak : White to pale blue

TP : Opaque to transparent
RI : 1.494 to 1.509
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : Pink to orange

Solubility : Hydrochloric acid, nitric acid

Magnetism : NoneRadioactivity : None


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