TAENITE
Taenite – (Fe,Ni) – is a native iron-nickel element that occurs in meteorites and in some very specific terrestrial geological situations.
It is classified in the Iron Group. It can contain Cu, Co, P, S, and C and is strongly magnetic.
1. Characteristics
Crystal system: Cubic hexaoctahedral.
Color: Grayish white, silvery white,
Habit: Small lamellae, grains, scales, spherulites. Large masses (40kg) with kamacite.
Cleavage: No.
Tenacity: Malleable, flexible.
Twinning: No.
Fracture: No information available.
Mohs Hardness: 5 – 5.5
Parting: No.
Streak: Light gray.
Lustre: Metallic.
Diaphaneity: Opaque.
Density (g/cm³): 7.8 – 8.2
2. Geology and Deposits
Taenite is an important component of meteorites. In lunar rocks, it occurs as spherulites.
In terrestrial geological situations, it can be found in serpentinized nickeliferous ultramafic rocks and in mafic igneous rocks that have assimilated carbon under reducing conditions.
It also occurs detrital as particles or spherulites in sands (placers).
3. Mineral Associations
It occurs associated with olivine, troilite (FeS), native iron, cohenite (Fe3C), kamacite (Fe,Ni), moissanite (SiC), schreibersite ((Fe,Ni)3P), plessite (intergrowth of taenite and kamacite), oldhamite ((Ca,Mg)S), awaruite (Ni3Fe), daubréelite (FeCr2S4), graphite and allabogdanite ((Fe,Ni)2P).
4. Transmitted Light Microscopy
This does not apply, as taenite is completely opaque.
5. Reflected Light Microscopy
Sample preparation: No information available.
PLANE POLARIZED LIGHT – PPL
Reflection color: Dark gray, similar in color to common silicates.
Pleochroism: No.
Reflectivity: ~7%
Bireflectance: No.
CROSSED POLARIZED LIGHT – XPL
Isotropy / Anisotropy: Isotropic.
Internal reflections: No.
May be confused with: Taenite is very similar to many common minerals, its identification require consideration of paragenesis. In theory, its strong magnetism and the absence of a prominent partition differentiate it from magnetite.
