Jun 3 2014
Brianite is a phosphate mineral that was first identified in an iron meteorite.
The mineral was named in honor of Brian Harold Mason, a New Zealandic-American meteoriticist, mineralogist, and geochemist.
Properties of Brianite
The following are the key properties of Brianite:
- Cell Data
- Space Group: P21/a
- a = 13.36(5)
- b = 5.23(2)
- c = 9.13(3)
- β = 91.2(2)°
- Z = 4
- Crystal Data
- Monoclinic
- Point Group: 2/m
- As anhedral grains, to 0.2mm
- Twinning: Polysynthetic on {100}, showing a lamellar structure in polarized light
- X-ray Powder Pattern: 2.625 (10), 3.734 (9), 2.679 (9), 1.875 (9), 2.718 (8), 3.344 (7), 2.230 (7)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| P2O5 |
46.9 |
47.27 |
| Na2O |
22.1 |
20.64 |
| CaO |
18.8 |
18.67 |
| MgO |
12.6 |
13.42 |
| FeO |
0.5 |
- |
| Total |
100.9 |
100.00 |
- Optical Properties
- Optical Class: Biaxial (–)
- Orientation: Extinction ^ lamellae ≈ 2°–3°
- α = 1.598(1)
- β = 1.605(1)
- γ = 1.608(1)
- 2V(meas.) = 63°–65°
- 2V(calc.) = 66°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 3.09 g/cm3
note: Specific gravity of Brianite = 3.13 g/cm3 |
| Photoelectric |
PEBrianite = 3.06 barns/electron
U = PEBrianite x ρElectron density = 9.43 barns/cm3 |
| Fermion index |
Fermion index = 0.0084
Boson index = 0.9915 |
Radioactivity
|
Brianite is not radioactive
|
How to Identify Brianite
Brianite is colorless, with vitreous luster, and white streak.
It has a transparent appearance, with a density of 3 g/cm3, and a relative hardness ranging from 4 to 5.
Global Distribution
Brianite is widely distributed in the Dayton finest (very fine-grained) octahedrite meteorite.
Occurrence of Brianite and Useful Mineral Association
Brianite occurs as a very rare component in phosphate nodules in an iron meteorite.
The minerals that are closely associated with brianite include troilite, sphalerite, graphite, taenite, kamacite, schreibersite, enstatite, albite, whitlockite, and panethite.
References