Jun 11 2014
Bobfergusonite was named to honor Emeritus Professor Robert Bury Ferguson (1920- ), a Canadian mineralogist at the University of Manitoba in Winnipeg, Canada, especially for his contributions to pegmatite mineralogy.
Properties of Bobfergusonite
The following are the key properties of bobfergusonite:
- Cell Data
- Space group: P21/n
- a = 12.776-12.843
- b = 12.478-12.518
- c = 10.966-11.035
- β = 97.21°- 97.47°
- Z = 4
- Crystal Data
- Monoclinic
- Point group: 2/m
- As equant anhedral crystals, to 1cm, and in nodular aggregates
- X-ray powder pattern: 3.054 (100), 2.082 (67), 2.869 (66), 2.508 (53), 2.712 (49), 1.575 (43), 2.902 (37)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| P2O5 |
45.2 |
43.8 |
43.75 |
| MnO |
31.7 |
32.2 |
36.44 |
| Al2O3 |
7.5 |
4.9 |
5.24 |
| Fe2O3 |
6.9 |
7.4 |
8.20 |
| Na2O |
6.8 |
6.3 |
6.37 |
| CaO |
1.2 |
0.6 |
- |
| FeO |
0.3 |
3.6 |
- |
| MgO |
0.3 |
0.4 |
- |
| H2O |
0.3 |
0.3 |
- |
| ZnO |
0.1 |
0.3 |
- |
| Total |
100.3 |
99.8 |
100.00 |
- Optical Properties
- Optical class: Biaxial (+)
- Pleochroism: Moderate; X = Y = yellow-orange; Z = orange
- Orientation: Y = b; X a = 10°
- Absorption: Z > X≃Y
- α = 1.694(1); β = 1.698(1); γ = 1.715(2)
- 2V(meas.) = 46.4(2)°
- 2V(calc.) = 52°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 3.40 g/cm3
note: Specific gravity of Bobfergusonite = 3.54 g/cm3 |
| Photoelectric |
PEBobfergusonite = 10.07 barns/electron
U = PEBobfergusonite x ρ electron density = 34.27 barns/cm3 |
| Fermion index |
Fermion index = 0.0014057662
Boson index = 0.9985942338 |
Radioactivity
|
Acanthite is not radioactive
|
How to Identify Bobfergusonite
Bobfergusonite can be identified in the field by its color variations, such as greenish-brown and reddish-brown. Its transparent to sub-opaque form has {010} perfect cleavage. This mineral has a resinous luster, with yellowish-brown streak. The fracture on this mineral is brittle.
The density of bobfergusonite is 3.54 g/cm3, with a hardness of 4 – approximate to fluorite.
Global Distribution
Bobfergusonite is distributed in the following places:
- Canada - From the Gotcha claim, on an island in Cross Lake, Manitoba
- Argentina - San Luis, Chacabuco Department, Nancy pegmatite
Occurrence of Bobfergusonite and Useful Mineral Association
Bobfergusonite occurs in an uncommon primary mineral in the intermediate zone of a granite pegmatite enriched in manganese and fluorine.
It is often associated with minerals such as beusite, fillowite, triplite, apatite, and alluaudite.
References