Aegirine (NaFeSi₂O₆) is the sodium-iron end-member of the alkali clinopyroxene group, forming long prismatic black to dark-green crystals in alkaline igneous rocks. The Mt. Saint-Hilaire (Quebec) and Khibiny Massif (Russia) localities produce world-class aegirine on syenite and nepheline pegmatite matrix.
Key Facts
- Mohs hardness 6.
- Monoclinic; long prismatic crystals with strong vertical striations.
- Forms in alkaline igneous rocks (syenites, phonolites) and high-pressure metamorphic blueschists.
- Diagnostic mineral of agpaitic alkaline rock suites.
- Closes the major clinopyroxene quartet with diopside, augite, and hedenbergite.
Notable Localities
Mt. Saint-Hilaire (Quebec, Canada) and Khibiny Massif (Kola Peninsula, Russia) produce world-class specimens. Malawi alkaline complex and Greenland yield additional collector material.
Found at these Localities
- Kola Peninsula Alkaline Complexes (科拉半岛碱性杂岩)
- Mont Saint-Hilaire (圣希莱尔山(魁北克))
- Murun Massif (穆伦碱性杂岩(西伯利亚))
