Jun 12 2014
Aegirine was named after Aegir, the Scandinavian sea-god in Norse mythology, by a vicar and mineralogist named H.M.T. Esmark, who found the mineral at Laven, Langesundsfjorden in 1834. This mineral belongs to the pyroxene group.
Properties of Aegirine
The following are the key properties of aegirine:
- Cell Data
- Space group: C2/c (synthetic).
- a = 9.658
- b = 8.795
- c = 5.294
- β = 107.42°
- Z = 4
- Crystal Data
- Monoclinic
- Point group: 2/m
- Prismatic
- Displaying {110}, with blunt to steep terminations, to 35cm, striated lengthwise, can be bent or twisted
- In sprays of acicular crystals, fibrous, in radial concretions
- Twinning: Simple and lamellar twinning common on {100}
- X-ray powder pattern: 2.900 (100), 6.369 (90), 4.416 (80), 2.983 (70), 2.4701 (60), 1.7293 (60), 1.3975 (60)
- Chemical Composition
| Elements |
Content 1 |
| SiO2 |
51.35 |
| Fe2O3 |
28.66 |
| Na2O |
12.66 |
| FeO |
2.24 |
| Al2O3 |
2.15 |
| CaO |
1.25 |
| TiO2 |
1.10 |
| H2O- |
0.17 |
| K2O |
0.15 |
| H2O+ |
0.12 |
| MgO |
0.10 |
| Total |
99.95 |
- Optical Properties
- Optical class: Biaxial (-); varieties rich in Ca, Mg, Fe2+ are (+)
- Pleochroism: X = emerald-green, deep green; Y = grass-green, deep green, yellow; Z = brownish-green, green, yellowish-brown, and yellow
- Orientation: X ^c = -10° to 12°; Y = b; Z ^ a = 6°-28°
- Dispersion: r > v, moderate to strong
- Absorption: X > Y > Z
- α = 1.722-1.776; β = 1.780-1.820; γ = 1.795-1.836
- 2V(meas.) = 60°-70°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 3.44 g/cm3
note: Specific gravity of aegirine = 3.52 g/cm3 |
| Photoelectric |
PEAegirine = 8.29 barns/electron
U = PEAegirine x ρ electron density = 28.56 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Aegirine is not radioactive
|
How to Identify Aegirine
Aegirine can be identified in the field by its color variations, such as green, greenish-black, reddish-brown, and black. Its sub-transparent to translucent to opaque form has distinct cleavage. This mineral has a vitreous–resinous luster, with a yellowish-gray streak. The fracture on this mineral is brittle.
The density of aegirine is 3.5 to 3.54 g/cm3, with a hardness of 6 to 6.5 - between orthoclase and pyrite.
Global Distribution
Aegirine is distributed in the following places:
- Norway - At Rundemyr, near Kongsberg; from Skaadoe, near Brevik; on Laven and other islands, Langesundsfjord; and at Drammen and Arendal
- Sweden - In the AlnÄo complex
- Greenland - At Narssarssuk
- Spain - At Huesca, Huesca Province
- Tanzania - From Oldonyo Dili
- Malawi - Large crystals from Mt. Malosa, Zomba district
- Canada - Mont Saint-Hilaire, Quebec
- USA - From Pitcairn, Russell, and LaSalle, St. Lawrence Co. and at Natural Bridge, Jefferson Co. New York; at Magnet Cove, Hot Spring Co. and from Granite Mountain, near Little Rock, Pulaski Co. Arkansas; in the Bear Paw Mountains, Hill Co. Montana
- Russia - From the Lovozero and Khibiny massifs, Kola Peninsula
Occurrence of Aegirine and Useful Mineral Association
Aegirine occurs commonly in alkalic igneous rocks, carbonatites, and pegmatites. It also occurs in regionally metamorphosed schists, gneisses, and iron formations; in blue-schist facies rocks, and from sodium metasomatism in granulites.In some cases it occurs as an authigenic mineral in some shales and marls.
It is often associated with minerals such as potassic feldspar, catapleiite, riebeckite, aenigmatite, arfvedsonite, astrophyllite, eudialyte, serandite, nepheline, and apophyllite.
References