Aegirine
Image: No machine-readable author provided. <a href="//commons.wikimedia.org/w/index.php?title=User:Kluka&action=edit&redlink=1" class="new" title="User:Kluka (page does not exist)">Kluka</a> assumed (based on copyright claims). (CC BY-SA 3.0)
Mineral NameAegirine
Chemical FormulaNaFe³⁺Si₂O₆
Mohs Hardness5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorpale yellowish gray
Cleavagegood on {110}
Fractureuneven
Specific Gravity3.55
Colorsblack, dark green, greenish black
Transparencytranslucent
Type LocalityKola Peninsula, Russia
Mineral GroupSilicates
Usescollector, minor industrial
Associated Mineralsapatite, nepheline, feldspar
Rarityuncommon
Description
This specimen displays radiating aggregates of black, acicular (needle-like) aegirine crystals embedded in a lighter, granular matrix.
Geological Context
Aegirine typically forms in alkaline igneous rocks such as nepheline syenites, phonolites, and carbonatites, often found in associated pegmatites.
