Sep 26 2013
Brianroulstonite was named after Brian V. Roulston (1948– ), a geologist and specialist in evaporite deposits.
Properties of Brianroulstonite
The following are the key properties of brianroulstonite:
- Cell Data
- Space group: Pa
- a = 17.367(4)
- b = 8.079(2)
- c = 8.693(2)
- β = 121.56(2)°
- Z = 2
- Crystal Data
- Monoclinic, pseudohexagonal
- Point group: m
- As thin micaceous {010} lamellae, to 0.5 mm, in aggregates
- Twinning: About [102] on {010}, ubiquitous but observed only by X-ray diffraction.
- X-ray powder pattern: 8.10 (10), 4.04 (4), 3.56 (2), 2.834 (2), 2.535 (2), 2.276 (2), 7.06 (1)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| B2O3 |
[33.92] |
28.76 |
28.80 |
| CaO |
32.85 |
27.85 |
27.84 |
| K2O |
0.05 |
| Cl |
13.79 |
11.69 |
11.73 |
| H2O |
[40.44] |
34.29 |
34.28 |
| -O = Cl2 |
3.11 |
2.59 |
2.65 |
| Total |
[117.94] |
[100.00] |
100.00 |
- Optical Properties
- Optical class: Biaxial (-)
- Orientation: Y = a; Z = b; X ^ c = 30°
- α = 1.506(2); β = 1.527(2); γ = 1.532(2)
- 2V(meas.) = 56(1)°
- 2V(calc.) = 51.4°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 1.98 g/cm3
note: Specific gravity of brianroulstonite = 1.93 g/cm3 |
| Photoelectric |
PEBrianroulstonite = 3.32 barns/electron
U=PEBrianroulstonite x ρ electron density= 6.58 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
| Radioactivity |
Brianroulstonite is not radioactive |
How to Identify Brianroulstonite
Brianroulstonite can be identified in the field by its white color, though it is sometimes colorless. Its transparen-translucent form has {010} perfect cleavage. This mineral has a vitreous luster with white streak. The fracture on this mineral is flexible. The density of brianroulstonite is 1.97 g/cm3 with a hardness of 5 – approximately the same as apatite.
Global Distribution
Brianroulstonite is mainly found in the Penobsquis evaporite deposit, near Sussex, New Brunswick, Canada.
Occurrence of Brianroulstonite and Useful Mineral Association
Brianroulstonite occurs very rarely in residues from halite–sylvite evaporites. It is often associated with minerals such as halite, hilgardite, fluorite, pringleite, trembathite, sellaite, hematite, muscovite, penobsquisite, and ‘clay’.
References