All of our aegirine comes from Mount Malosa in the Zomba District of Malawi, and often occurs in association with feldspar, smoky quartz and other minerals.
Aegirine occurs as dark green to black monoclinic prismatic crystals. It has a glassy luster and perfect cleavage. It has a hardness of from 5 to 6 on the The Mohs scale and the specific gravity is 3.2 to 3.4.
It falls within the clinopyroxene group of inosilicates. It is the sodium endmember of the aegirine-augite series with NaFeSi2O6 as its chemical formula in which the iron is present as Fe3+. In the aegirine-augite series the sodium may be replaced by calcium with iron(II) and magnesium replacing the iron(III) to balance the charge. Aluminium can also substitute for the iron(III). It can also known as acmite which is a fibrous, green-colored variety.