Aegirine
Mineral NaFeSi2O6
Also called Acmite
About it
Long, sharp black to green prisms with pointed tips in nepheline syenite and pegmatite; Mount Malosa, Malawi, gives large crystals with feldspar, as does Mont Saint-Hilaire.
- Type
- Mineral
- Group
- Silicate (inosilicate), pyroxene group
- Formula
- NaFeSi2O6
- Hardness (Mohs)
- 6
- Specific gravity
- 3.5–3.6
- Streak
- pale yellowish grey
- Lustre
- vitreous (glassy), resinous
- Crystal system
- Monoclinic
- Colours
- black, dark green, greenish brown
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- good in two directions at nearly 90°
Typical values: real specimens vary. For more, see mindat.org.