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Chemical Formula | NaFeSi2O6 |
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Composition | Sodium iron silicate. |
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Color | Black, brown, dark green, reddish black |
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Streak | Gray |
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Hardness | 6 - 6½ |
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Crystal Forms and Aggregates |
(Monoclinic) Usually in long, thin, prismatic crystals, with a pointed pyramid on top ("clinopinicoidal"), almost always embedded in a matrix. Fibrous masses and grainy aggregates also occur. |
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Transparency | Opaque. Translucent in thin splinters. |
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Specific Gravity | 3.5 - 3.6 |
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Luster | Vitreous |
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Cleavage | 1,2 - prismatic at cleavage angles of 87º
and 93º (characteristic of minerals in the pyroxene group). May also exhibit parting in one direction. |
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Fracture | Uneven, splintery |
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Tenacity | Brittle |
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Other Names |  Acmite |
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In Group | Silicates ; Inosilicates ; Pyroxene group |
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Uses | Steep, prismatic, well-shaped specimens are highly valued to collectors. |
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Striking Features | Unusually steep crystals, hardness, and color. |
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Popularity (1-4) | 2 |
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Prevalence (1-3) | 3 |
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Demand (1-3) | 2 |
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Distinguishing Similar Minerals |
Augite - lacks steep pyramidal crystals Tourmaline - lacks steep pyramidal crystals |
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Commonly Occurs With |
Albite, Nepheline, Quartz, Sodalite, Biotite, Augite, Riebeckite |
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Noteworthy Localities |
Aegirine has been found in: Langesunfjord, Norway; Narssarssuaq, Greenland; the Kola Peninsula of Russia; Mt. Molosa, Malawi; and Pocos de Caldas, Brazil. In North America, the premier locality is Magnet Cove, Garland Co., Arkansas. Aegirine was also found in Beemerville, New Jersey, and in the High Mountains of Montana. In Canada, excellent specimens, perhaps the finest of all, come from Mont St. Hilaire, Quebec. |
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Picture Icon Links |
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Picture Links | Sorry. No Images currently available. |
