aegirine-augite

mineral

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July 23, 2026

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Aegirine-augite is a mineral belonging to the pyroxene group, specifically a sodium and iron silicate with the chemical formula NaFe⁺³Si₂O₆. It is commonly found in alkaline igneous rocks like syenites and syenite pegmatites, as well as in crystalline schists. Aegirine-augite forms a continuous chemical series with aegirine, where calcium replaces sodium and magnesium and aluminum substitute for iron. The name "acmite" is sometimes used for crystals with the composition NaFeSi₂O₆, while aegirine typically refers to darker green to greenish-black crystals of the same composition. Aegirite is another name for acmite.12

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aegirine
…a continuous chemical series with aegirine-augite, in which calcium replaces sodium, and magnesium and aluminum replace iron. In this series, the name acmite is given to crystals with the composition NaFeSi₂O₆ as well as to the reddish brown or greenish black pointed crystals approximating that composition. Aegirine generally is restricted…
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…a continuous chemical series with aegirine-augite, in which calcium replaces sodium, and magnesium and aluminum replace iron. In this series, the name acmite is given to crystals with the composition NaFeSi₂O₆ as well as to the reddish brown or greenish black pointed crystals approximating that composition. Aegirine generally is restricted…
Read More