Sep 26 2013
Brannockite is a member of the osumilite group of minerals. The mineral was first discovered in 1973 from the Foote Mineral Co. mine in Kings Mountain, Cleveland County., North Carolina, USA. It was named after Dr. Kent C. Brannock, Chemist, Kingsport, TN.
Properties of Brannockite
The following are the key properties of Brannockite:
- Cell Data
- Space Group: P6/mcc
- a = 10.002(2)
- c = 14.263(3)
- Z = 2
- Crystal Data
- Hexagonal
- Point Group: 6/m 2/m 2/m
- In very thin hexagonal plates, with {0001} dominant, to 1 mm
- Twinning: Common, ⊥ [0001], observable only by X-ray study
- X-ray Powder Pattern: 4.109 (10), 2.905 (9), 7.141 (8), 4.343 (8), 5.714 (7), 8.693 (6), 2.681 (6)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| SiO2 |
65.8 |
64.7 |
| SnO2 |
28.2 |
27.05 |
| Li2O |
3.75 |
4.02 |
| K2O |
3.72 |
4.23 |
| Na2O |
0.74 |
- |
| Total |
102.2 |
100 |
- Optical Properties
- Optical Class: Uniaxial (-)
- ω = 1.567
- ε = 1.566
- Estimated Properties
| Electron density |
Bulk density (electron density)=2.87 g/cm3
note: Specific gravity of Brannockite =2.98 g/cm3 |
| Photoelectric |
PEBrannockite = 62.57 barns/electron
U= PEBrannockite x ρ Electron density= 179.36 barns/cm3 |
| Fermion index |
Fermion index = 0.05
Boson index = 0.95 |
| Radioactivity |
Brannockite is barely detectable |
How to Identify Brannockite
Brannockite is a colorless mineral with transparent appearance, vitreous luster and white streak. It exhibits fluorescent luminescence and brittle fractures as displayed by glasses and most of the non-metallic minerals. The density of the mineral is 2.98 g/cm3, and its hardness ranges from 5 to 6.
Global Distribution
Brannockite is widely distributed in the Foote mine, Kings Mountain, Cleveland Co., North Carolina, USA.
Occurrence of Brannockite and Useful Mineral Association
Brannockite occurs in the late hydrothermal portions of a Li-Sn-rich pegmatite, vugs and on flat fracture surfaces. It is closely associated with the quartz, albite, stannian titanite, tetrawickmanite, pyrite and bavenite.
References