Aegirine
Image: James St. John (CC BY 2.0)
Mineral NameAegirine
Chemical FormulaNaFeSi2O6
Mohs Hardness6
Crystal Systemmonoclinic
Lustervitreous
Streak Colorpale yellowish-gray to greenish-gray
Cleavagegood on {110} at nearly 90 degrees
Fractureuneven
Specific Gravity3.55
Colorsdark green, greenish-black, black
Transparencytranslucent to opaque
Type LocalityIce River Complex, British Columbia, Canada
Mineral GroupSilicates (Pyroxene Group)
Usescollector's mineral, scientific research
Associated Mineralssodalite, albite
Rarityuncommon
Description
Aegirine in this specimen appears as very dark green, prismatic crystals, forming part of a cavity-filling within a pegmatite. It contrasts with the blue sodalite and whitish albite.
Geological Context
Aegirine is a characteristic mineral of alkali-rich igneous rocks, such as nepheline syenites and their associated pegmatites. This specimen formed as a cavity-filling in a pegmatitic syenite within the Ice River Complex.
