Best viewed using Adobe Flash Player (8 or higher).
Download hereGENERAL DESCRIPTION
Aegirine (formely acmite) is a sodium and iron silicate, which forms in alkaline rocks, such as nephelinic syenites and pegmatites. Aegirine also develops sometimes in rocks of contact metamorphism.
Aegirine belongs to the group of pyroxenes, it is one more precisely a clinopyroxene. It is regularly associated other mineral species, like augite, nepheline, nosean, orthoclase...
The crystals of aegirine are prismatic, elongated in shape, sometimes striated and they show often a very sharp termination. Crystals are brown-black to black in color but also translucent green to opaque. They can reach 30 cm in length.
Aegirine is rather widespread: superb crystals are found in British Columbia (green-emerald crystals of 10 cm in length) and at the Mont Saint-Hilaire (acicular crystals) in Canada, the Malosa Mount in Malawi (crystals of 20 cm, and finished crystals of 8 cm)...
In France, it is known at Puy of the Tâche in the Puy-de-Dôme, in Azinières in Aveyron, in Montgenèvre and Saint-Véran in Hautes-Alpes.
The place of conservation of the type of this species (originating in the southern coast of Norway: Langesunfjord and Bukerud) are not known.
Did you know? this mineral is one of the few pyroxenes that contains only ferric iron.
HISTORY : Name inspired from Aegir, god of the Sea in the Scandinavian mythology. The first samples discovered come from Norway.
Species first described in 1835 by Jöns Jacob Berzélius (1179-1848), Swedish chemist
Type-locality: Rundemyr, Buskerud, Norvège et Skadön, Larvik, Norvège
CHEMICAL FORMULA : Na (Fe3+) Si2O6
CRYSTAL SYSTEM : Monoclinic
COLOR : Deep to redish brown, black
DIAPHANIETY : Translucide to opaque
LUSTER : Vitreous
STREAK : Yellowish gray
MORPHOLOGIE : Prismatic crystals
HARDNESS : 6
CHEMICAL CLASS: 3,576
DENSITY : VIII - Silicates
GROUP : Pyroxen
STRUNZ CLASS BEFORE 2001 : 8/F.1-140
STRUNZ CLASS AFTER 2001 : 9.DA.25
