Aegirine: Gemston Information
Aegirine is NaFe3+Si2O6 and forms translucent to opaque dark to bright green, brown to black prismatic monoclinic crystals with blunt to steep terminations and lengthwise striations. The hardness is 6 and the SG 3.50–3.60. The RI for the alpha, beta and gamma rays is 1.772–1.776, 1.780–1.820 and 1.795–1.836, biaxial negative with birefringence 0.045. Aegirine occurs in alkalic igneous rocks and in pegmatites. Good crystals come from several Norwegian locations, including Langesundfjord and large crystals have been found at Mt Malosa, Zomba district, Malawi.