Mineral Guide · Mineral
Aegirine is a sodium iron pyroxene with dark green to black prismatic crystals, usually formed in alkaline igneous environments.
Interactive 3D structure
Loading interactive structure...
Aegirine is a sodium iron silicate and a member of the clinopyroxene group. It is best recognised in collections by dark green to greenish-black prismatic crystals, often growing in cavities or on a contrasting matrix. The older name acmite is also encountered in mineralogical literature.
Aegirine has the ideal formula NaFe3+Si2O6 and crystallises in the monoclinic system. It is an inosilicate built from single chains of linked silicate tetrahedra. Aegirine commonly forms elongated prismatic crystals with a vitreous lustre and has a Mohs hardness around 6-6.5.
Typical colours range from deep green and olive green to greenish black, black and reddish brown. Strong pleochroism can be visible in thin sections, while hand specimens are often opaque or translucent at thin edges. The long prism faces may show lengthwise striations or sharp terminations.
Aegirine is characteristic of sodium-rich alkaline igneous rocks, including nepheline syenites, alkaline granites and related pegmatites. It also occurs in hydrothermal assemblages associated with alkaline complexes. Important localities include the Kola Peninsula in Russia, the Oslo region of Norway, Mont Saint-Hilaire in Canada, Greenland, Malawi and Namibia.
Colour alone is not sufficient to separate aegirine from other dark pyroxenes. The combination of a slender prismatic habit, monoclinic pyroxene structure, sodium-iron chemistry, locality and associated minerals provides a more reliable description. Sharp crystals on feldspar, nepheline or quartz matrix are especially informative for a collection.
In popular birthstone and zodiac guides, Aegirine is often associated with Aries and Scorpio. These zodiac crystal associations are part of modern spiritual culture and vary between traditions, countries and individual practitioners. They are not a mineralogical classification and should not be presented as a scientific property of the stone.
Crystal collectors and readers of esoteric symbolism may choose Aegirine for its colour, texture, locality and personal meaning. In crystal healing and meditation traditions, it may be described with themes such as focus, grounding, protection, calm or confidence, depending on the source. These symbolic interpretations can be useful for storytelling and personal reflection, but there is no reliable scientific evidence that a mineral changes health, energy, luck or destiny.
When choosing a Aegirine birthstone, zodiac crystal or spiritual gift, compare the actual specimen: natural colour, crystal habit, transparency, inclusions, locality and condition. A mineral guide is more reliable when symbolic associations are kept separate from tested physical properties and from the description of an individual piece.
Reviewed by NotOnlyRocks Editorial Team
Last reviewed: 31 August 2026