Oct 21 2013
Farringtonite is a monoclinic-prismatic mineral containing phosphorus, oxygen and magnesium. It was named after Oliver Cummings Farrington, an authority on meteorites.
Properties of Farringtonite
The following are the key properties of Farringtonite:
- Cell Data
- Space Group: P21/a
- a = 8.79(1)
- b = 8.22(2)
- c = 5.07(1)
- β = 120.5(5)°
- Z = 2
- Crystal Data
- Monoclinic
- Point Group: 2/m
- Subhedral to euhedral grains, to 2 mm, and as rims on olivine.
- X-ray Powder Pattern: 3.443 (100), 3.85 (67), 2.411 (48), 4.09 (40), 4.34 (38), 3.65 (37), 2.122 (33)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| P2O5 |
53.2 |
53.9 |
54.00 |
| MgO |
43.1 |
44.9 |
46.00 |
| FeO |
4.1 |
2.7 |
|
| MnO |
0.19 |
0.13 |
|
| SiO2 |
0.09 |
0.07 |
|
| CaO |
0.07 |
0.08 |
|
| Total |
100.8 |
101.8 |
100.00 |
- Optical Properties
- Optical Class: Biaxial (+)
- Orientation: Z ^ c = 16°–17°
- α = 1.540(2)
- β = 1.544(2)
- γ = 1.559(2)
- 2V(meas.) = 47°–55°
- Estimated Properties
| Electron density |
Bulk density (electron density)=2.72 g/cm3
note: Specific gravity of Farringtonite =2.75 g/cm3 |
| Photoelectric |
PEFarringtonite = 1.74 barns/electron
U= PEFarringtonite x ρElectron density= 4.73 barns/cm3 |
| Fermion index |
Fermion index = 0.02
Boson index = 0.98 |
| Radioactivity |
Farringtonite is not radioactive |
How to Identify Farringtonite
Farringtonite can be identified in the field by its wax yellow or white color and it has good cleavage and a white streak. The density of farringtonite is 2.74 g/cm3.
Global Distribution
Farringtonite is distributed in the following places:
- Springwater, Krasnojarsk, Zaisho, Imilac
- Port Orford pallasite meteorites.
Occurrence of Farringtonite and Useful Mineral Association
Farringtonite occurs as a rare component in pallasite meteorites, rimming and cementing olivine nodules. It is closely associated with kamacite, schreibersite, troilite, stanfieldite and olivine.
References